Oxygen free radicals and calcium homeostasis in the heart

Molecular and Cellular Biochemistry, Oct 1994

Many experiments have been done to clarify the effects of oxygen free radicals on Ca2+ homeostasis in the hearts. A burst of oxygen free radicals occurs immediately after reperfusion, but we have to be reminded that the exact levels of oxygen free radicals in the hearts are yet unknown in both physiological and pathophysiological conditions. Therefore, we should give careful consideration to this point when we perform the experiments and analyze the results. It is, however, evident that Ca2+ overload occurs when the hearts are exposed to an excess amount of oxygen free radicals. Though ATP-independent Ca2+ binding is increased, Ca2+ influx through Ca2+ channel does not increase in the presence of oxygen free radicals. Another possible pathway through which Ca2+ can enter the myocytes is Na+−Ca2+ exchanger. Although, the activities of Na+−K+ ATPase and Na+−H+ exchange are inhibited by oxygen free radicals, it is not known whether intracellular Na+ level increases under oxidative stress or not. The question has to be solved for the understanding of the importance of Na+−Ca2+ exchange in Ca2+ influx process from extracellular space. Another question is ‘which way does Na+−Ca2+ exchange work under oxidative stress? Net influx or efflux of Ca2+?’ Membrane permeability for Ca2+ may be maintained in a relatively early phase of free radical injury. Since sarcolemmal Ca2+-pump ATPase activity is depressed by oxygen free radicals, Ca2+ extrusion from cytosol to extracellular space is considered to be reduced. It has also been shown that oxygen free radicals promote Ca2+ release from sarcoplasmic reticulum and inhibit Ca2+ sequestration to sarcoplasmic reticulum. Thus, these changes in Ca2+ handling systems could cause the Ca2+ overload due to oxygen free radicals.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://link.springer.com/content/pdf/10.1007%2FBF00944207.pdf

Oxygen free radicals and calcium homeostasis in the heart

O x y g e n f r e e r a d i c a l s a n d c a l c i u m h o m e o s t a s i s i n t h e h e a r t Masanori Kaneko 0 1 Yuji Matsumoto 0 1 Hideharu Hayashi 0 1 2 Akira Kobayashi 0 1 Noboru Yamazaki 0 1 0 Address for offprints: Dr. Masori Kaneko, The Third Department of Internal Medicine, Hamamatsu University School of Medicine , 3600 Handa-cho, Hamamatsu 431-31 , Japan 1 The Third Department of Internal Medicine 2 Photon Medical Research Center, Hamamatsu University School of Medicine , Hamamatsu 431-31 , Japan A b s t r a c t Many experiments have been done to clarify the effects of oxygen free radicals on Ca2+homeostasis in the hearts. A burst o f oxygen free radicals occurs immediately after reperfusion, but we have to be reminded that the exact levels of oxygen free radicals in the hearts are yet unknown in both physiological and pathophysiological conditions. Therefore, we should give careful consideration to this point when we perform the experiments and analyze the results. It is, however, evident that Ca2+overload occurs when the hearts are exposed to an excess amount of oxygen free radicals. Though ATP-independent Ca 2+binding is increased, Ca2+ influx through Ca2§ channel does not increase in the presence o f oxygen free radicals. Another possible pathway through which Ca 2. can enter the myocytes is Na+-Ca2+exchanger. Although, the activities ofNa§ +ATPase and Na+-H+exchange are inhibited by oxygen free radicals, it is not known whether intracellular Na § level increases under oxidative stress or not. The question has to be solved for the understanding of the importance o f Na § Ca z+exchange in Ca 2+influx process from extracellular space. Another question is 'which way does Na+-Ca2+exchange work under oxidative stress? Net influx or efflux of Ca 2§?' Membrane permeability for Ca 2+may be maintained in a relatively early phase of free radical injury. Since sarcolemmal Ca2+-pumpATPase activity is depressed by oxygen free radicals, Ca 2§extrusion from cytosol to extracellular space is considered to be reduced. It has also been shown that oxygen free radicals promote Ca 2§ release from sarcoplasmic reticulum and inhibit Ca 2+ sequestration to sarcoplasmic reticulum. Thus, these changes in Ca 2+ handling systems could cause the Ca 2+overload due to oxygen free radicals. (Mol Cell Biochem 139: 91-100, 1994) **This paper was published in the focussed issue "Calcium and Calcium Binding Proteins in the Cell" (Guest Editor: G.N. Pierce). Molecular and Cellular Biochemistry 135: 99-108, 1994..Kluwer Academic Publishers regret the publication of the uncorrected version. "sarcolemma; myofibrils; Na+/Ca2§ exchange; sarcoplasmic reticulum; cardiac contraction; Ca2+pump - I n t r o d u c t i o n During the last decade, the role of oxygen free radicals in myocardial ischemia-reperfusion injury has been studied extensively. Although, the most important pathways through which free radicals m a y be f o r m e d during ischemiareperfusion have not been defined precisely, several lines o f evidence have shown that a burst o f oxygen free radicals occurs immediately after reperfusion [ 1-4 ]. It has been also reported that oxygen free radicals have the ability to cause the dysfunction o f the heart, and that various types of free radical scavengers have protective effects on ischemiareperfusion injury [ 5-10 ]. These data suggest that oxygen free radicals is one o f the crucial factors in ischemiareperfusion injury. It is also well accepted that intracellular Ca 2+ o v e r l o a d p l a y s an i m p o r t a n t role in i s c h e m i a reperfusion injury [ 11-16 ]. Ca2+ overload could have serious consequences for the myocyte through activation o f a variety of enzymes such as proteases, lipases, and phospholipases [17] or ATPase [ 11, 12 ]. In addition, Ca2§ is actively accumulated and precipitated with phosphate in the matrix space of mitochondria [ 18 ]. This process is associated with inhibition of ATP synthesis [ 18 ] via mitochondrial oxidative phosphorylation and the ATP synthetase. Therefore, clarification of the relationship between oxygen free radicals and Ca 2+ homeostasis is necessary to understand the detail mechanisms for cellular injury in myocardial ischemia-reperfusion. The purpose of the present treatise is to discuss on this subject. In the first section, we discuss on the effects of oxygen free radicals on Ca2. handling systems in the heart. In the next section, effects of oxygen free radicals on intracellular Ca2+concentration are discussed. Effects o f o x y g e n free radicals on Ca 2§ h a n d l i n g s y s t e m s in the heart Cytosolic Ca2§overload can occur either because of increased Ca2§influx from extracellular space to cytosoi or because of insufficient Ca2+extrusion from cytosol. Cytosolic Ca2+concentration is also affected by subcellular Ca2+store sites such as sarcoplasmic reticulum. Therefore, the following discussion is divided into three parts. The first part is the effects of oxygen free radicals on Ca2+influx from the extracellular space to intracellular space. These processes include ATPindependent Ca 2§ binding, Ca 2+ channels, adrenergic receptors, Na+-Ca2+ exchange, Na+-K+ ATPase, Na+-H§ exchange, and permeability o f cardiac sarcolemmal membranes. The second part is the effects of oxygen free radicals on Ca 2+extrusion systems, which include Na+-Ca2+exchange and Ca2+ pump ATPase of sarcolemmal membranes. The final part is the effects o f oxygen free radicals on Ca 2+ translocating processes of sarcoplasmic reticulum. I." Ca2+ influx f r o m extracellular space to intracellular space It is well accepted that excitation-contraction coupling in mammalian heart include two critical Ca2+components. One component o f Ca 2+ comes directly from influx across the sarcolemmal membrane, and another component of Ca2+is derived from the sarcoplasmic reticulum via the process of Ca2+-induced Ca2+-release [ 19, 20 ]. The Ca2+-channel and the Na§ 2+ exchanger are recognized as responsible for this transsareolemmal influx of Ca 2§ [21], though Na§ 2+ exchanger also operates to produce a net effiux of Ca2§(22, 23]. 1. A TP-independent Ca2*-binding The sources o f Ca 2+ that enters the cell across the sarcolemma are considered to be the extracellular space and Ca2*binding sites within the sarcolemmal membranes [ 24-26 ]. Langer et al. [ 24-26 ] reported that membrane bound Ca2+ in cardiac cell is a superficial store o f Ca2§ which becomes available for entry upon excitation of the myocardium. Kinetic studies of Ca 2+ binding with sarcolemmal membrane in the absence of ATP have revealed the presence o f both low-affinity, high-capacity CaZ+-binding site and highaffinity, low-capacity Ca2*-binding site [ 26 ]. The amount of Ca2+that enters the cell is a major determinant o f the concentration of Ca z+ at the myofilaments during systole, and is a major determinant of the level of contactile force as a result [ 26 ]. In fact, ATP-independent Ca2§ in heart sarcolemma has been shown to exhibit linear relationship with the contaetile force development in the normal myocardium [ 24-28 ]. We have examined the effects of oxygen free radicals on this ATP-independent CaZ+-binding activity in rat heart sarcolemmal membrane [ 29 ]. In the presence of xanthine plus xanthine oxidase or hydrogen peroxide, both low- and highaffinity Ca2+-binding activities were increased after 5 min incubation. Philipson et al. [ 30 ] showed that more than 80% of Ca2+was bound to membrane phospholipids at physiological level of extracellular Ca2§ Since oxygen free radicals are known to promote the peroxidation of membrane phospholipids [ 31 ], it is likely that the changes in ATP-independent Ca2+-binding by oxygen free radicals are due to alterations in the phospholipid composition o f the membrane. 2. Ca2§ channels Ca2+ channels are intrinsic membrane glycoproteins that participate in the regulation oftransmembrane ion flow and cellular function in the heart [ 32-34 ]. Caz+ channels open in response to changes in membrane potential and allow Ca2+to enter cells. This inward movement of Ca2§ depolarizes the heart cell membrane and contributes to the plateau phase of the action potential, pacemaker activity, and impulse conduction [ 35-37 ]. In addition, the influx of Ca 2§ causes a transient rise in intracellular Caz§ concentration, which in turn can initiate the cardiac contraction [ 38-41 ]. We have examined the effects o f oxygen free radicals on the binding of Ca2+channel antagonists by employing [3H]nitrendipine as a ligand. Isolated rat heart membranes were incubated with various types of oxygen free radicals-generating system, and the assay of the [3H]-nitrendipine binding activity revealed that the maximal number o f binding sites (Bmax) was reduced in a time-dependent manner without any significant changes in the binding constant (Kd); a significant reduction of Bmax was seen after incubating the membranes with free radical-generating systems for a 10min-period [ 42 ]. These results indicate that oxygen free radicals may reduce the number o f voltage-dependent Ca 2+ channels and this change may contribute towards decreasing the voltage-dependent Ca2+ influx of the cardiac cells. In electrophysiological studies, Burrington et al. [ 43 ], Hayashi et al. [ 44 ], Beresewicz et al. [ 45 ], and Jabr and Cole [ 46 ] have reported that oxygen free radicals produced an initial prolongation o f action potential duration of rat and guinea pig ventricular myocytes, and that the prolongation of action potential duration was followed by a shortening of duration. Pallandi et al. [ 47 ] reported that xanthine oxidase-generated free radicals reduced the amplitude after 20 to 30 min exposure but did not affect the duration of the action potential in guinea pig ventricular strips. Cerbai et al. [ 48 ] reported a prolongation of action potential duration by dihydroxyfumarate in guinea pig ventricular myocytes. On the other hand, Nakaya et al. [ 49 ] reported that organic hydroperoxides produced decreases in both the amplitude and the duration o f action potential of guinea pig papillary muscles and canine Purkinje fibers, and that it took 10 min o f superfusion with hydrogen peroxides for the changes in resting potential and action potential to occur. It was, therefore, shown that the effects of free radicals on action potential duration were variable according to duration of the perfusion and to the species of free radicals. On the other hand, action potential duration can be influenced not only by Ca2. current but by K§ current. Goldhaber et al. [ 50 ] observed that 1 mM H202 or 1 mM xanthine plus 0.01 U/ml xanthine oxidase caused a rapid decrease in the amplitude o f the Ca 2+ current in patchclamped guinea pig single ventricular myocytes. Cerbai et al. [ 48 ] also reported that Ca2. current was rapidly reduced by the superfusion of guinea pig ventricular myocytes with 5 mM dihydroxyfumarate (DHF). They observed that after 2 rain o f exposure to DHF, the peak Ca 2+ current was decreased about 70% of its initial value, without any appreciable modification of its kinetics. Tan" et al. [ 51 ] showed that rose bengal-generated oxygen free radicals suppressed Caz+ currents in single frog atrial cells. Nakaya et al. [ 52 ] also reported that 10 to 30 ktM cumene hydroperoxide decreased the Ca z+currents of guinea pig ventricular cells. These results indicate that Ca2§ influx through the voltage-dependent Ca 2+channels could not be the cause of Ca 2§ overload during the exposure to oxygen free radical-generating systems. 3. Adrenergic receptors The [3-adrenergic receptor-stimulatory guanine nucleotidebinding protein (Gs) - adenylate cyclase system is a plasma membrane-bound protein assembly consisting of three maj o r components [ 53, 54 ]. The heterotrimetric guanine nucleotide-binding regulatory proteins couple with extracellular receptors and cause stimulation (Gs) or inhibition (Gi) of the effector enzyme adenylate cyclase, which is the primary regulator of the intraceltular concentration of the second messenger cyclic AMP (cAMP) [ 53-55 ]. In the heart, ct subunit o f the Gs(Gsct) plays a central role in the regulation of cardiac function [56] as in addition to transducing ]3-adrenergic receptor-mediated activation of adenylate cyclase. The Gsc~ regulates the phosphorylation o f Ca2§channels indirectly by cAMP-dependent protein kinase [ 57 ], and it activates voltage-dependent Ca2+channels by a more direct interaction [ 58 ]. Cyclic AMP-dependent protein kinases can also promote the phosphorylation of other regulatory proteins such as phospholamban in the sarcoplasmic reticulum and troponin I in myofibrils [ 59 ]. Therefore, the changes in 13-receptor - Gs - adenylate cyclase system can affect Ca2+homeostasis in the heart. Haenen et al. [ 60 ] reported that although a low concentration (1 10-7 - 1 10-3 M) of hydrogen peroxide increased Bmax for [125I]-iodocyanopindrol binding, while a high concentration (1 x 10-t M) of hydrogen peroxide decreased Bmax. We observed that both Bmax and Kd for [3H]dihydroalprenol (DHA) binding were increased by xanthine plus xanthine oxidase after 10 min of incubation in rat heart. One mM of hydrogen peroxide increased the Kd value whereas Bmax was unaffected [ 61 ]. When a hydrophilic ligand, [3H]-CGP- 12177, was used for the [3-adrenergic receptor assay, an increase in Kd value without any significant changes in Bmax was seen on treating the membrane with xanthine plus xanthine oxidase [ 61 ]. We also examined the direct effects of hydrogen peroxide on Gs activity, and observed that hydrogen peroxide (0.1 to 10 mM) did not cause any significant effects on both Gs activity and the coupling in the 13-adrenergic receptor - Gs - adenylate cyclase system in rat cardiac membranes [ 62 ]. Will-Shahab et al. [ 63 ], Shimke et al. [ 64 ], and we [ 62 ] showed that adenylate cyclase activity was depressed by oxygen free radicals. Furthermore, in the presence of oxygen free radical-generating systems, cAMP productions after stimulation with GTP, GTP + (1)-isoproterenol, Gpp(NH)p, and Gpp(NH)p + (1)isoproterenol were reduced [ 62 ]. Therefore, it seems that the changes in [3-adrenergic receptor systems under oxidative stress may not lead to Ca2+overload in the heart. 4. Na+-Ca 2+ exchange, Na§ § ATPase, and Na+-H+ exchange The Na+-Ca 2+exchange system can move Ca2§either into or out of the cytosol, across the plasma membrane, in exchange for Na + [ 65 ]. The net direction of Ca 2§movement mediated by the exchanger depends on the Na § and/or the Ca 2§ electrochemical gradient, the stoichiometry, and the membrane potentials during the action potential [ 65 ]. Since the reversal potential for the exchange (EN~ca) is slightly positive to the resting membrane potential during diastole, there is a small net outward movement of Ca2., mediated by the exchange that operates in parallel with the CaZ+-pump ATPase to maintain the low resting Ca2+ level in the cytosol. During the upstroke of the action potential, the driving force becomes positive, and this tends to drive Ca 2+into the cells in exchange for Na § The net Ca2§ entry mediated by the exchange may continue through the plateau phase of the action potential. Then as the cell repolarizes because of the opening of K§ channels, the driving force becomes negative; this results in net effiux of Ca2+mediated by the exchange operating in the Ca z+ effiux mode [ 66 ]. Na§ 2§ exchange is also affected by the changes in the activities of Na+-K§ ATPase and Na*-H+ exchange. Inhibition of the Na+-K+ ATPase produces a rise in intracellular level of Na§ [ 67, 68 ]. An elevation of the intracellular Na§ will lead to the rise in intracellular Ca2§either by a decreased Ca2§ effiux or by an increased Ca2§ influx via Na*-Ca2§ exchange [23]. The inhibition of the Na§ + ATPase also results in an intracellular acidification that is thought to be a consequence o f a rise in intracellular Ca 2. produced via Na§ z+exchange [ 69-71 ]. Furthermore, measurements of intracellular Na§ have shown that inhibitors of Na§ + exchange decrease the rise in intracellular Na § which was produced by ouabain [ 70, 72-74 ]. These results suggest that even in the presence of ouabain, Na+-H+ exchange is producing a net Na§ influx which increases intracellular Ca2§ via Na+-Ca2+exchange [ 23, 70 ]. Thus, these three ion transporting systems can affect each other, and play important roles in Caz+ handling in cardiac cells. Kramer et al. [ 75 ] demonstrated that Na+-K§ ATPase activity was reduced by oxygen free radical-generating system (dihydroxyfumarate and Fe3§ in canine cardiac sarcolemmai membranes. Kukreja et al. [ 78 ] also showed that the inhibition of Na§ + ATPase activity was seen in the presence o f H202, HzO2 plus Fe2+, H O C I , NH2C1, or PMA-stimulated human neutrophils whereas the enzyme activity was not changed by xanthine plus xanthine oxidase in dog heart sarcolemmal vesicles. Bhatnagar et al. [ 77 ] observed that superfusion of frog ventricular single cells with tert-butyi hydroperoxide(t-BHP) increased intracellular Na§ which could result from a decrease in Na § effiux via Na+-K+ pump. On the other hand, Xie et al. [ 102 ] reported that both Na§ §ATPase and Na§ § exchange activities were reduced by xanthine plus xanthine oxidase and that Na+-H§ exchange was more sensitive to oxidative stress than that of Na+-K§ ATPase. Furthermore, they observed that 45Ca2+uptake by myocytes was increased in the presence of ouabain, however, 45Ca2§ uptake was decreased by xanthine plus xanthine oxidase. Their data suggest that intracellular Na+may not increase to the level which can promote Ca2§ influx via Na§ 2§ exchange under oxidative stress, since Na§ + exchange is inhibited by free radicals as well as Na*-K§ATPase. These data support that heart sarcolemmal activities of Na§ + ATPase and Na+-H§ exchange are reduced by oxygen free radicals. Kim et al. [ 76 ] reported that ischemiareperfusion o f isolated guinea pig heart reduced Na+-K§ ATPase activity and specific [3H]-ouabain binding to the enzyme; these effects of ischemia-reperfusion were prevented to various degrees by oxygen free radical scavengers, such as superoxide dismutase, catalase, dimethylsulfoxide, histidine, or vitamin E, or by the xanthine oxidase inhibitor, allopurinol. It was, therefore, suggested that an increase in free radicals during ischemia-reperfusion was implicated in reduced Na+-K+ ATPase activity. The direct effects o f oxygen free radicals on Na§ ~§ exchange is discussed in the next part of this chapter. 5. Membrane permeability, membrane fluidity, and phosphatidylethanolamine N-methylation One o f the main targets of oxygen free radicals appears to be the polyunsaturated fatty acids of the membrane phospholipids [ 31 ]. Lipid peroxidation can be initiated by the interaction o f a reactive oxidant with a fatty acid to form a lipid radical, which then can react rapidly with 02 to form the corresponding peroxy radical. This peroxy radical can then attack a neighboring fatty acid to form the hydroperoxide and a new alkyl radical. This reaction will propagate until two radical species unite in a chain-terminating reaction to form a non-radical product, or until a radical reacts with an agent, such as ct-tocopherol, that forms stable radicalls [ 31 ]. Such chain reactions can result in substantial membrane damage and can change ion permeability and fluidity of membranes [ 78-81 ]. Ytrehus et al. [ 82 ] observed the fragmentation o f sarcolemma with subsequent leakage of cell organelles into the interstitium after 10 min Langendorff perfusion o f rat heart with 0.96 mM hypoxanthine plus 0.025 U/ml xanthine oxidase. Levedev et al. [ 83 ] reported that Ca2§ permeability o f bilayer lipid membranes consisting ofphosphatidylcholines in a mixture with cholesterol was increased when the membranes were formed from oxidizing lipids or when initiators of lipid peroxidation, ascorbate and iron ions, were added to both sides of the membrane. On the other hand, Bhatnagar et al. [ 77 ] reported that plasma membrane permeability for Ca2+remained intact even after 30 min exposure to t-BHP in single cells isolated from frog ventricle. Hata et al. [ 84 ] also showed that rat heart sarcotemmal permeability for Ca2+and Na § was not changed upon treatment with 2 mM xanthine plus 0.03 U/ml xanthine oxidase, 0.5 mM HzOz, or 0.01 mM H202 plus 0.01 mM Fe2. for 30 rain. Thus, it seems likely that sarcolemmal membrane permeability for Caz+may be maintained in a early phase o f he injury, while it is increased in a final stage of membrane damage caused by oxygen free radicals. It may be difficult for the cells to maintain the cell functions in the situation in which cell membrane permeability for Ca2§ is increased. Lipid peroxidation of membrane phospholipids also results in the changes in membrane fluidity. Many researchers reported that membrane fluidities were decreased by the p e r o x i d a t i o n o f p h o s p h o l i p i d vesicles, e r y t h r o c y t e s , m i c r o s o m e s , and mitochondrial m e m b r a n e s [ 8 5 - 9 1 ] , whereas Grzelinska et al. [ 92 ] showed increased membrane fluidity following peroxidation of erythrocytes membrane. We [ 93 ] observed that heart sarcolemmal, sarcoplasic reticular, and mitochondrial membrane fluidities were decreased by 2 mM xanthine plus 0.03 U/ml xanthine oxidase during 5 to 30 min of incubation. However, these membrane fluidities were increased after 60 min of incubation. The decrease in the membrane fluidity can be due to lipid peroxidation o f membrane phospholipids by oxygen free radicals. The later increase in the fluidity is considered to reflect the disruption o f the membranes, membrane permeability for Ca2+may increase in such condition. The intramembranal rearrangement o f the two major membrane phospholipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), can be regulated by phospholipid N-methylation [ 94 ]. Phospholipid N-methylation has been considered to have important implication for cell membrane properties such as membrane fluidity [ 95 ], membrane-bound enzyme activities [ 96-99 ], and 13-adrenergic receptors [100]. The PE N-methylation in rat heart sarcolemmal and sarcoplasmic reticular membranes was reduced by oxygen free radicals [ 101 ]. Thus, oxygen free radicals can modify the membrane integrity by altering the PE Nmethylation process as well as lipid peroxidation. II. Ca2+extrusion from intracellular space to extracellu Iar space To maintain the levels of Ca2§ion in cytosol and subcellular Ca2+store sites, Ca2+which entered the cells from the extracellular space during the action potential, has to be pumped out from the cytosol to extracellular space. It is believed that heart sarcolemma contains two important mechanisms for extruding Ca2+; Na+-Ca2+ exchange and CaR§ ATPase [ 103-105 ]. 1. Na+-Ca2+ exchange In the heart, Na+-Ca2+ exchange is thought to function primarily as a mechanism for pumping Ca 2+out of the cell, it is, however, possible that Na+-Ca 2§ exchanger can also promate the net entry o f Ca 2+ into the cell under certain circumstances such as membrane depolarization as described in the previous part. The effects of oxygen free radicals on Na+-Ca2§ exchange is controversial. Reeves et al. [ 106 ] reported that Na§ 2§exchange system in sarcolemmal vesicles of bovine ventricular tissue was stimulated by both oxidizing and reducing agents. Na+-Ca2+exchange activity was stimulated by preincubating the vesicles with 1 ~tM FeSo4 plus 1 mM dithiothreitol (DTT) which is known to generate superoxide anion radical, H202, and hydroxyl radical, xanthine plus xanthine oxidase, Fe2§plus H202, or GSH plus GSSG [ 106 ]. However, the exchange activity was not affected by H202, GSH, or GSSG, alone [ 106 ]. Based on these data, they considered that the redox agents may activate exchange activity by promoting thiol-disulfide interchange in the carrier protein [ 106 ]. Shi et al. [ 107 ] reported that exposure of bovine heart sarcolemmal vesicles to 50 gM FeSo4 plus 1 mM DTT for 1 to 40 min stimulated Na+-Ca2§ exchange and decreased the apparent Km for Ca 2§ of Na*~-dependent Ca2§ uptake. Conversley, others [ 102, 108-110 ] reported that Na+-Ca 2+ exchange activity was reduced by oxygen free radicals. Kutryk and Pierce [ 108] showed that Na*-Ca2+ exchange activity in canine heart sarcolemmal vesicles was depressed by 50 I.tmol/mg of protein H202 or by cholesterol oxidase. Xie et al. [ 102 ] also observed that Na§ 2+exchange activity in rat myocytes was decreased by 1 mM xanthine plus 0.08 U/mol xanthine oxidase after 30 min of incubation. Furthermore, Hata et al. [ 84 ] showed that various types of oxygen free radical-generating systems inhibited the Na+-Ca2+ exchange activity in sarcolemmal membrane vesicles isolated from rat, bovine, canine, and porcine hearts. Bersohn et al. [ I 12], Daly et al. [ 109 ], Meon et al. [ 110 ], and Dixon et al. [ 111, 113 ] reported that heart sarcolemmal Na+-Ca 2§ exchange activity was depressed in hearts subjected to ischemia-reperfusion or h y p o x i a reoxygenation, and that the reduced activity o f Na+-Ca2+ exchange in ischemia-reperfused hearts was prevented by the addition of free radical scavengers to the perfusate [113]. 2. Ca2+opump ATPase o f sarcolemmal membrane We [ 114, 115 ] observed the effects of oxygen free radicals on Ca2+-pump ATPase activity and the mechanism for the effects. The Ca2+ATPase activity and ATP-dependent Ca 2+ accumulation in rat heart sarcolemmal inside-out vesicles were reduced by xanthine plus xanthine oxidase, H202, or H20: plus Fe2+both in a dose- and a time-dependent manner; a significant inhibition of the activity was seen after 1 min of incubation. Since Ca2+-pump ATPase in cardiac sarcolemma is intimately involved in the extrusion o f Ca z+ across the cell membrane [ 114 ], the inhibition o f sarcolemmal CaZ§ ATPase by oxygen free radicals could lead to decrease Ca 2§extrusion from the cytosol, resulting in an increase in cytosolic Ca2+concentration. Mechanisms f o r the changes in heart sarcolemmal ion-transporting systems by oxygen free radicals To investigate the role of sulfhydryl groups in causing depression of the sarcolemmal CaZ§ activities, we [ 115] examine the following aspects in heart sarcolemmal membranes: 1. the effects ofsulfhydryl-reducing agents, such as DDT or cysteine on the depression of CaZ§ activities due to oxygen free radicals, 2. the effects of sulfhydryl groups reagents, such as Nethytmaleimide (NEM), on Ca2*-pumpATPase activity, and 3. the effects of oxygen free radicals on sulfhydryigroups. The inhibition of sarcolemmal Ca2+-pump activities by oxygen free radicals was prevented by the addition of DTT or cysteine in a dose-dependent manner [ I 15]. NEM inhibited Ca2+-pump activity both in a dose- and a time-dependent manner [115]; DTT and cysteine prevented the changes in Ca2+-pump activity because of NEM [115]. Hearts sarcolemmal sulfhydryl groups were depressed by various types of oxygen free radical-generating systems both in a doseand a time-dependent manner; free radical scavengers showed protective effects on the sulfhydryl groups depression by oxygen free radicals [115]. Furthermore, there was a significant correlation between changes in sarcolemmal Ca2§ ATPase activity and sarcolemmal sulfhydryl groups [115]. These results indicate that oxygen free radicals depress the heart sarcolemmal Ca2+-pump activity by modifying the sulfhydryl groups in the sarcolemmal membrane. In addition, because sulfhydryl groups are known to regulated other membrane-bound ion-transporting systems such as Na§ + ATPase, Na+-Ca2+ exchange, and voltagedependent Ca2+channel of sarcolemma, Ca2+release protein and CaZ+-pumpATPase of sarcoplasmic reticulum [ 84, 106, 116-128 ], it is likely that the oxidation of sulfhydryl groups in the membrane-bound ion-transporting systems may lead to depression of the activities due to oxygen free radicals. Not only the direct reactions of oxygen free radicals with membrane-bound enzyme proteins but lipid peroxidation of membrane phospholipids by free radicals can affect the enzyme activities. Accumulation of hydroperoxides resulted from peroxidation of membrane phopholipids can inactivate the enzymes activities by modifying the lipid microenvironment, by oxidizing amino acid residues, or by mediating polypeptide chain polymerization reactions [ 31 ]. III. Ca2§ processes o f sarcoplasmic reticulum Hess et al. [ 129-135 ] have studied the effects of various types of oxygen free radical-generating systems on Ca2§ transporting systems of cardiac sarcoplasmic reticulum. They observed that Ca2+-pump ATPase activity and steady-state Ca2+ uptake were depressed by free radicals [ 129-135 ]. Direct measurement of the number and turnover of the pump units indicated that the number of the units was unchanged but turnover rate was decreased by oxygen free radicals [ 131 ]. Furthermore, exposure to oxygen free radicals increased the passive permeability of the sarcoplasmic reticular vesicles to Ca2+, but the increased permeability p e r se was insufficient to explain the effects of oxygen free radicals on Ca2+pump ATPase activity [ 131 ]. Cumming and Holmberg et al. [ 136, 137 ] have studied the effects of free radicals, which was produced by the illumination of rose bengal, on the sheep cardiac sarcoplasmic reticulum Ca2§ release channel which was inserted into synthetic lipid bilayers. They found that Ca2+ release channel open probability was increased initially, and that continued illumination resulted in an irreversible loss of channel function and subsequent bilayer disruption [ 136-138 ]. They also showed that ryanodine binding in isolated cardiac membranes was reduced by oxygen free radicals, with associated degradation of a 340 kD protein, which is thought to be the ryanodine receptor and sarcoplasmic reticular Ca2§release channel complex [ 136-138 ]. Abramson et al. [118, 119] and Zaidi et al. [ 126 ] reported that oxidizing agents were found to induce rapid Ca2. efflux from actively loaded sarcoplasmic reticular vesicles isolated from rabbit skeletal muscle. These data indicate that when sarcoplasmic reticulum is exposed to oxygen free radicals, Ca2+release from sarcoplasmic reticulum to cytosol is promoted and Ca2+sequestration from cytosol into sarcoplasmic reticulum lumen is inhibited. Scherer et aI. [ 123 ] and other researchers [ 121, 122 ] suggested that decline in Ca2+-pump ATPase activity was due to oxidation of sulfhydryl groups as evidenced by the ability of sulhydryl groups reducing agents to prevent inhibition of the ATPase activity, the decline in sulfhydryl content of oxidized sarcoplasmic reticulum, and the ability of sulfhydryl groups binding agents to inhibit the Ca2+-pump ATPase activity. Salama's group showed that reactive disulfide compounds, which are known to specifically oxidize free SH sites via a thiol-disulfide exchange reaction, trigger Ca2§ release from sarcoplasmic reticular vesicles [ 116-119, 126 ]. Furthermore, they reported that sulfhydryl groups reducing agents can reverse the effects of reactive disulfide compounds [ 126 ]. Thus, the modification of sulfhydryl groups is important mechanism by which oxygen free radicals affect on Ca2§ systems in sarcoplasmic reticulum, as well as in sarcolemmal membrane. E f f e c t s o f o x y g e n free r a d i c a l s o n i n t r a c e l l u l a r C a 2+ c o n c e n t r a t i o n Electrophysiological studies have shown that the application of oxygen free radicals caused delayed after depolarization and aftercontraction, which indicate Ca2§ overload of the cell [ 44, 49 ]. It is, however, important to measure intracellular Ca2§ concentration during the application of oxygen free radicals. The development of calcium-sensitive fluorescent dyes has provided a new technique to monitor the changes in Ca2§ during the contraction cycle and to measure intracellular Caz+ concentration. Using this technique, the effects of oxygen free radicals on intracellular Ca 2+ concentration have been studied [ 44, 139-142 ]. Hayashi et al. [ 44 ] reported that rod-shaped myocytes became shortened or rounded (contracture) after the application of 0.1 and 1 mM H202 in isolated guinea pig ventricular myocytes, and that intracellular Ca 2§concentration ([Ca 2+]), measured by the fura-2 340/380 ratio, increased from the control values o f 53 and 68 nmol/l to 110 and 105 nmol/1 when cells were shortened during the perfusion o f 0.1 and 1 mM H202, respectively, Burton et al. [ 139 ] observed that exposure o f cultured rat ventricular myocytes to free radical-generating solution (2.3 mM purine, 0.01 U/ml xanthine oxidase, and 2.4 pM iron-loaded transferrin) altered [Ca2+]~: fura-2 fluorescence ratio which indicate [CaZ+]i was 639% o f the control value after approximately 3 0 - 7 0 min with cessation o f normal Ca2+transients. They also reported that there was no increase in [Ca2+]i when myocytes pretreated with 10 laM et-tochopherol for 18-24 hr were exposed to free radicals [ 139 ]. Josephson et aI. [ 140 ] reported that measurements in isolated rat ventricular myocytes loaded with indo1 d e m o n s t r a t e d rises in b o t h s y s t o l i c and d i a s t o l i c fluorescence ratio following exposure to the free radical-generating system ( l - 1 0 mM HzO2 plus Fe3+-nitrilotriacetate): the Ca2+overload was prevented by the Ca2+channel antagonist, nitrendipine, suggesting that the Ca2+overload occured largely due to Ca 2+ influx through voltage gated Ca2+channels. Liu et al. [ ! 41 ] reported that the effect o f oxidized low density lipoprotein (LDL) on the Ca 2+transients o f isolated rabbit cardiomyocytes using fura-2 technique. They observed that the systolic Ca2+concentration in transients was significantly increased after treatment with 100 gg of oxidized LDL cholesterol/ml for 16 min without any effect on the diastolic Ca2+concentration [ 141 ]. Eley et al. [ 142 ] showed exciting data concerning the effect o f oxygen free radicals on Ca 2+ homeostasis in isolated rabbit ventricular myocytes which were loaded with fura-2 and superfused with 100 gm HOC 1 under voltage-clamped conditions. In these experiments, they observed that the amplitude o f the Caz+ transients was reduced from 402 nM to 82 nM while [Ca2+]i increased from 78 nM to 265 nM within 200 seconds after HOCI addition: during this time, the amplitude o f the slow inward currents increased by 10%. This sustained steady-state rise in [Ca2§ occured even in the absence o f extracellular Caz+ but was virtually abolished by preexposure to 10 mM caffeine [ 142 ]. Furthermore, although washout o f HOC1 failed to induce recovery, subsequent exposure to the dithiol reducing agent dithiothreitol caused a rapid restoration o f both the steadystate [CaZ+]~ and Ca2+ transient amplitude. Therefore, they concluded that HOCI caused a rise o f [Ca2+]~ by inducing the release o f Ca2+from internal stores and by impairing cellular extrusion mechanisms, and that these effects occur through alteration o f protein thiol redox status [ 142 ]. R e f e r e n c e s 1. Arroyo CM , Kramer JH , Dickens BF , Weglicki WB : Identification of free radicals in myocardial ischemia/reperfusion by spin trapping with nitrone DMPO . FEBS Lett 221 : 101 - 104 , 1987 2. Bolli R , Patel BS , Jeroudi MO , Lai EK , McCay PB : Demonstration of free radical generation in "stunned" myocardium of intact dogs with the use of the spin trap alpha-phenyl N-tert-butyl nitrone . J Clin Invest 82 : 476 - 485 , 1988 3. Garlick PB , Davies MJ , Hearse DJ , Slater TF : Direct detection of free radicals in the reperfused rat heart using electron spin resonance spectroscopy . Circ Res 61 : 757 - 760 , 1987 4. Zweier JL , FtahertyJT, Weisfeldt ML : Direct measurementoffreeradical generation following reperfusion ofischemic myocardium . Pro Natl Sci USA 84 : 1404 - 1407 , 1987 5. Gupta M , Singal PK : Oxygen radical injury in the presence ofdesferal, a specific iron-chelating agent . Biochem Pharmaco136 : 3774 - 3777 , 1987 6. Przyklenk K , Whittaker P , Kloner RA : Direct evidence that oxygen free radicals cause contractile dysfunction in vitro . Circulation 78 ( Suppl II ): I1 -264, [ 988 7. Przyklenk K , Kloner RA : Superoxide dismutase plus catalase improve contractile function in the canine model of the "stunned myocardium" . Circ Res 58 : 148 - 156 , 1986 8. Bolli R , Zhu WX , Hartley CJ , Michael LH , Repine JE , Hess ML , Kukreja RC , Robert R : Attenuation of dysfunction in the postischemic "stunned" myocardium by dimethylthiourea . Circulation 76 : 45 ~ 468 , 1987 9. Chartat ML , O'Neill PG , Egan JM , Abernethy DR , Michael LH , Myers LH , Robert R , Bolli R : Evidence for a pathogenetic role ofxanthine oxidase in the"stunned" myocardium . Am J Physio1252: H566-H577 , 1987 10. Bolli R , Jeroudi MO , Pater BS , Arouma OI , Halliwell B , Lai EK , MeCay PB : Marked reduction of free radical generation and contractile dysfunction by antioxidant therapy begun at the time ofreperfusion . Circ Res 65 : 607 ~ 515 , 1989 i 1 . KatzAM, Reuter H : Cellular calcium and cardiac cell death . Am J Cardiol 44 : 188 - 190 , 1979 12. Nayler WG : The role ofcalcium in the ischemic myocardium . Am J Pathol 102 : 262 - 270 , 1981 13. Lee HC , MohabirR, SmithN, FranzMR, ClusinWT: Effect ofischemia on calcium-dependent fluorescence transients in rabbit hearts containing indo-l . Circulation 78 : 1047 - 1059 , 1988 14. Lee HC , Smith N , Mohabir R , Clusin WT : Cytosolic calcium transients from the beating mammalian heart . Proc Natl Acad Sci USA 252 : C441 ~ 449 , 1987 15. Marban E , Kitakaze M , Koretsune Y , Yue DT , Chacko VP , Pike MM : Quantification of [Ca~ § in perfused heart: Critical evaluation of the 5FBAPTAandnuclear magnetic resonance method as applied to the study of ischemia and reperfusion . Circ Res 66 : 1255 - 1267 , 1990 16. Steenbergen C , Murphy E , Levy L , London RE : Elevation in cytosolic free calcium concentration early in myocardial ischemia in perfused rat heart . Circ Res 60 : 700 - 707 , 1987 17. Farber JL , Chien KR , Mittnaeht S : The pathogenesis ofirreversible cell injury in ischemia . Am J Pathol 102 : 271 - 281 , 1981 18. Tsokos J , Bloom S : Effects of calcium on respiration and ATP contect of isolated, leaky, heart muscle cells . J Mol Cell Cardiol 9 : 823 - 836 , 1977 19. Fabiato A , Fabiato F : Calcium-induced release ofcalcium from the sarcoplasmic reticulum of skinnedcells from adult human, dog, cat, rabbit, rat, and frog hearts and from fetal and new-born rat ventricles . Ann NY Acad Sci 307 : 491 - 522 , 1978 20. Fabiato A : Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum . Am J Physiol 245 : C1 ~ 14 , 1983 21. Langer GA , FrankJS, Philipson KD : Ultrastructureand calcium exchange ofthe sarcolemma, sarcoplasmicreticulum and mitochondriaofthe myocardium . Pharmacol Ther 16 : 331 - 376 , 1982 22. Mullins LJ : The generation of electric currents in cardiac fibers by Na/Ca exchange . Am J Physiol 236 : CI03 ~ 2110 , 1979 23. Philipson KD , Ward R : Caz§transport capacity ofsarcolemmal Na+-Ca2+ exchange. Extrapolation of vesicle data to in vivo conditions . J Mol Cell Cardiol 18 : 943 - 951 , 1986 24. Bers DM , Langer GA : Uncoupling cation effects on cardiac contractility and sarcolemmal Ca binding . Am J Physio1237: H332-H341 , 1979 25. Bers DM , Philipson KD , Langer GA : Cardiac contractility and sarcolemmal calcium binding in several cardiac preparation . Am J Physio 240 : H576 - H583 , 1981 26. Langer GA : Calcium at the Sarcolemma: Its Role in Control of Myocardial Contraction . In: R.D. Nathan (ed). Cardiac muscle: The regulation of excitation and contraction . Academic Press, Orlando, 1986 ,pp 269 - 28 i 27. DhallaNS, Pierce GB , PanagiaV,SingalPK, BeamishRE: Calciummovements in relation to heart function. Basic Res Cardio177 : 117 - 139 , 1982 28. DhallaNS, Smith CI , Pierce GN , ElimbanV,MakinoN, KhatterJC: Heart sarcolemmal cation pumps and binding sites . In: H. Rupp (ed). Regulation of heart function. Thiame-Stratton , New York, 1986 , pp 126 - 136 29. Kaneko M , Singal PK , DhallaNS: Alterations in heart sarcolemmal Ca2§ ATPaseand CaZ§ activitiesdue to oxygen free radicals . Basic Res Cardiol 85 : 45 - 54 , 1990 30. Philipson KD , Bets DM , NishimotoAY:The role ofphospholipids in the Ca2§binding of isolated sarcolemma . J Mol Cell Cardiol 12 : 1159 - 1173 , 1980 31. Freeman BA , Crapo JD : Biology of Disease; free radicals and tissue injury . Lab Invest 47 : 412 - 426 , 1982 32. BeanBP: Classesofcalcium channelsin vertebratecells . Annu Rev Physiol 51 : 367 - 384 , 1989 33. Pelzer D , Pelzer S , McDonald TF : Properties and regulation of calcium channels in muscle cells . Rev Physiol Biochem Pharmacol 114 : 108 - 207 , 1990 34. Porzig H : Pharmacological modulation of voltage-dependentCa channets in intact cells . Rev Physiol Biochem Pharmacol 114 : 209 - 262 , 1990 35. Carmeliet E , Vereecke J : Electrogenesis ofthe action potential and automaticity . In: Handbook of Physiology , vol I, The Heart; Section 2: The CardiovascularSystem ,AmericanPhysiologicalSociety,Bethesda,Maryland, 1979 , pp 269 - 334 36. Dorr Th , Denger R , DorrA, Trautwein W: Ionic currents contributing to the action potential in single ventricular myocytes of the guinea pig studied with action potential clamp . Pflugers Arch 416 : 230 - 237 , 1990 37. Noble D : The surprising heart: A review ofrecent progress in cardiac electrophysiology . J Physiol (Lond) 353 : 1 - 50 , 1984 38. Gibbons WR , Fozzard HA : Relationshipsbetween voltage and tension in sheep cardiac Purkinje fibers . J Gen Physio165 : 345 - 365 , 1975 39. Nabeuer M , Callewaert G , Cleemann L , Morad M : Regulationof calcium releaseis gatedby calcium current,not gating charge,in cardiacmyocytes . Science 244 : 800 - 803 , 1989 40. Tanabe T , Mikami A , Numa S , Beam KG : Cardiac-type excitation coupling in dysgenie skeletal muscle injected with cardiac dihydropyridine receptor eDNA . Nature 344 : 451 - 453 , 1990 41. Trautwein W , McDonald TF , Tripathi O : Calcium condactance and tension in mammalian ventricular muscle . PflugersArch 354 : 55 - 74 , 1975 42. Kaneko M , Lee SL , WolfCM, Dhalla NS : Reduction of calcium channel antagonist binding sites by oxygen free radicals in rat heart . J Mol Cell Cardiol 21 : 935 - 943 , 1989 43. Barfington PL , Meier Jr CF , WeglickiWB: Effects of free radicals on the canine myocyte action potential . Fed Proc 44 : 1578 , 1986 44. Hayashi H , Miyata H , Watanabe H , Kobayashi A , Yamazaki N : Effects of hydrogen peroxide on action potentials and intracellular Ca:+ concentration of guinea pig heart . Cardiovasc Res 23 : 767 - 773 , 1989 45. Beresewisz A , Horackova M : Alterations in electrical and contractile behaviorofisolatedcardiomyocytesby hydrogen peroxide: Possible ionic mechanisms . J Mol Cell Cardio123 : 899 - 918 , 1991 46. Jabr RI , Cole WC : Alterations in electrical acfvity and membrane currents induced by intracellularoxygen-derived free radical stress in guinea pig ventricular myocytes . Circ Res 72 : 1229 - 1244 , 1993 47. PaUandiRT, Perry MA , CampbellTJ: Proarrhythmiceffectsofan oxygenderived free radical generating system on action potentials recorded from guinea pig ventricular myocardium: A possible cause of reperfusion-induced arrhythmias . Circ Res 61 : 50 - 54 , 1987 48. Cerbai E , Ambrosio G , Porciatti F , Chiariello M , Giotti A , Mugelli A : Cellularelectrophysiologicalbasis foroxygenradical-inducedarrhythmias: A path-clamp study in guinea pig ventricular myocytes . Circulation 84 : I773 - 1782 , 199t 49. Nakaya H ,TohseN, KannoM: Electrophysiologicalderangementsinduced by lipidperoxidation in cardiac tissue . Am J Physio1253: H1089-H 1097 , 1987 50. GoldhaberJ1, Ji S , Lamp ST , WeissJN: Effects ofexogenousfree radicals on electromechanicalfunctionand metabolismin isolatedrabbitand guinea pig ventricle: Implication for ischemia and reperfusion injury . J Clin Invest 83 : 1800 - 1809 , 1989 51. Tarr M , Valenzeno DP : Modification of cardiac ionic currents by photosensitizer-generated reactive oxygen . J Mol Cell Cardiol 23 : 639 - 649 , 1991 52. Nakaya H , Takeda Y , Tohse N , Kanno M : Mechanism of the membrane depolarizationinduced by oxidative stress in guinea-pig ventricular cells . J Mol Cell Cardio124 : 523 - 534 , 1992 53. Levitzki A : 13 - Adrenergicreceptors and their mode of coupling to adenylate cyclase . Physiol Rev 66 : 819 - 854 , 1986 54. GilmanAG: G protein transducerof receptorgenerated signals . Annu Rev Biochem 56 : 615 ~ 549 , 1987 55. lkegayaT, Kobayashi A , Hong RB , Masuda H , Kaneko M , Yamazaki N : Stimulatory guanine nucleotide-binding protein and adenylate cyclase activitiesin Bio 14.6cardiomyopathichamsters at the hypertrophic stage . Mol Cell Biochem 1t0 : 83 - 90 , 1992 56. Robishow JD , Foster KA : Role of G proteins in the regulation of the cardiovascular system . Annu Rev Physiol 51 : 229 - 244 , 1989 57. Mattera R , Graziano ME YataniA ,Zbou Z , Graf R , Codina J , Bimbaumer L , Gilman AG , Brown AM : Splice variants of the ot subunit of the G protein G activate both adenylyl cyclase and calcium channels . Science 243 : 804 - ~ 806, 1989 58. YataniA, BrownAM: Rapid l3 -adrenergicmodulation ofcardiaccalcium channel currents by a fast G protein pathway . Science 245 : 71 - 74 , 1989 59. Karozewski P , Bartel S , Krause EG : Differential sensitivity to isoprenalineoftroponin I and pbospholambanphosphorylationin isolatedrat hearts . Biochem J 266 : 115 - 122 , 1990 60. Haenen G , Dansik PV , Vermeulen NPE , Timmerman H , BastA: The effect of hydrogen peroxide on [3-adrenoceptorfunction in the heart . Free Radic Res Commun 4 : 243 - 249 , 1988 61. KanekoM, Chapman DC , Ganguly PK , Beamish RE , Dhalla NS : Modificationofcardiacadrenergicreceptorsby oxygenfreeradicals . AmJ Physiol 260 ( Heart Circ Physio129 ): H821 - H826 , 1991 62. Masuda H , Kaneko M , Hong RB , Ikegaya T , Hayashi H , Kobayashi A , YamazakiN: Effectsofhydrogen peroxide on stimulatory guanine nucleotide-binding protein in rat heart . Jpn Circ J 1993 , in press 63. Will-Shahab L , Schimke I , Haberland A , Kotner I : Responsiveness of cardiac adenylate cyclase in the normal and ischemic myocardium. Role of oxygen free radicals . Biomed BiochimActa 46 : 427 - 432 , 1987 64. Shimke I , HaberlandA, Will-Shahab L , Kuttner I , Paies B : Free radical induced damage of cardiac sarcolemma (SL) and activity loss of breceptor adenylate cyclase system (b-RAS). A comparison of the time course . Biomed Biochim Acta 48 : 69 - 72 , 1989 65. Langer GA : Sodium-calcium exchange in the heart . Annu Rev Physiol 44 : 435449 , 1982 66. Blaustein MP : Sodium/calcium exchange and the control of contractility in cardiac muscle and vascular smooth muscle . J Cardiovasc Pharmacol 12 ( suppl 5 ): 536 - 568 , 1988 67. Deitmer JW , Ellis D : The intracellular sodium activity of cardiac Purkinje fibres during inhibition and re-activation of the Na-K pump . J Physiol 284 : 241 - 259 , 1978 68. DeitmerJW, Ellis D : Changes in the intracellularsodiumactivityof sheep heart Purkinje fibres produced by calcium and other divalent cations . J Physiol (Lond) 277 : 437 - 453 , 1978 69. Vaughan-Jones RD , Lederer W , Eisner Da: Ca2+ions can affect intracellular pH in mammalian cardiac muscle . Nature 301 : 522 - 524 , 1983 70. Kim D , Cragoe EJ , Smith TW : Relationships among sidium pump inhibition, sodium-calcium exchange, and sodium-hydrogen exchange activities and calcium-hydrogen interaction in cultured chick heart cells . Circ Res 60 : 185 - 193 , 1987 71. Kim D , Smith TW : Cellular mechanisms underlying calcium-proton interaction in cultured chick ventricular cells . J Physiol (Lond) 398 : 391 - 340 , 1988 72. Kim D , Smith TW : Effect ofamiloride and ouabain on contractile state, Ca fluxes and cellular Na content in cultured chick heart cells . Mol Pharmacol 29 : 363 - 37 I, t 986 73. Frelin C , Vigne P , Lazdunski M : The role of the Na+/H§exchange system in cardiac cells in relation to the control of the internal Na*concentration . J Biol Chem 259 : 8880 ~ 885 , 1984 74. Satoh H , Hayashi H , Kobayashi A , YamashitaY, Yamazaki N : Regulation of [Na§ and [CaZ+]~in guinea pig myocytes-study by fluorescent indicators SBFI and FLUO-3- . Am J Physiol 1994 ,in press 75. Kramer JH , Mak IT , WeglickiWB: Differentialsensitivity of canine cardiac sarcolemmal and microsomal enzymes to inhibitionby free radicalinduced lipid peroxidation . Circ Res 55 : 120 - 124 , 1984 76. Kim MS , Akera T : Oz free radicals: Cause of ischemia-reperfusion injury to cardiac Na+- K*-ATPase.Am J Physio1252: H252-H257 , 1987 77. Bhatnagar A , Srivastava SK , Szabo G : Oxidative stress alters specific membrane currents in isolated cardiac myocytes . Circ Res 67 : 535 - 549 , 1990 78. Kukreja Re , WeaverAB, Hess ML : Sarcolemmal sodium-potassiumATPase: Inactivation by neutrophil-derived free radicals and oxidants . Am J Physiol 259 : HI330 - H1336 , 1990 79. Fong KL , McCay PB , PoyerJL: Evidencethat pemxidationoflysosomal membranes is initiated by hydroxyl free radicals produced during ravin enzyme activity . J Biol Chem 248 : 7792 - 7797 , 1973 80. Player TJ , Hulton HO : The effectof lipid peroxidation on the calciumaccumulating ability of the microsomal fraction isolated from chicken breast muscle . Biochem J 174 : 17 - 22 , 1978 81. Hicks M , Gebicki JM : A quantitative relationship between permeability and the degree ofperoxidation in ufasome membranes . BiochemBiophys Res Comm 80 : 704 - 708 , 1978 82. Ytrehus M , Myklebust R , Olsen R , Mjes OD : Ultrastructural changes induced in the isolated rat heart by enzymaticallygeneratedoxygen radicals . J Mol Cell Cardiol 19 : 379 - 389 , 1987 83. LebedevAV, Levitsky DO , Loginov VA , Smirnov VN : The effect of primary products of lipid peroxidation on the transmembrane transport of calcium ions . J Mol Cell Cardiol 14 ( suppl 3 ): 99 - 103 , 1982 84. Hata T , Kaneko M , Beamish RE , Dhalla NS : Influence of oxygen free radicals on heart sarcolemmal Na+-Caz§exchange . Coron Art Dis 2 : 397 - 407 , 1991 85. Barrow DA , Lentz BR : A model for the effect of lipid oxidation on diphenylhexatriene fluorescence in phospholipid vesicles . Biochim Biophys Acta 645 : 17 - 23 , 1981 86. Rice-Evans C , Hochstein P : Alterations in erythrocyte membrane fluidity by phenylhydrazine-induced peroxidation of lipids . Biochem Biophys Res Comm 100 : I537 - 1542 , 1981 87. Eichenberger K , Bohni P , Winterhalter KH , Kawato S , Richter C : Microsomal lipid peroxidation causes an increase in the order of the membrane lipid domain . FEBS Lett 142 : 59 - 62 , 1982 88. BruchRC, Thayter WS : Differentialeffect oflipidperoxidation on membrane fluidityas determinedby electron spin resonance probes . Biochim Biophys Acta 733 : 216 - 222 , 1983 89. Niki E , Komuro E , Takahashi M , Urano S , Ito E , Terao K : Oxidative hemolysis oferythrocytes and its inhibition by free radical scavengers . J Biol Chem 263 : 19809 - 19814 , 1988 90. Vladimirov VA , Olenev VI , Suslova TB , Cheremisina ZP : Lipid peroxidation in mitochondrial membrane . In: R. Paoletti and D. Kritchevsky(eds). Advancesin lipidresearch.AcademicPress ,NewYork, 1980 , 17 : pp 173 - 249 91. WatanabeH, KobayashiA,YamamotoT, Suzuki S , Hayashi H , Ymnazaki N : Alterations of human erythrocyte membrane fluidity by oxygen-derived free radicals and calcium . Free Rad Biol Med 9 : 507 - 514 , 1990 92. Grzelinska E , Bartasz G , Gwozdzinski K , Leyko W : Aspin-label study ofthe effect of gamma radiation on erythrocyte membrane. Influence of lipid peroxidationon membrane structure . Int J Radiat Bio136 : 325 - 334 , 1979 93. Kaneko M , YuanGX, Suzuki H , Matsumoto Y , KobayashiA, Yamazaki N : Susceptibility of cardiac membranes to oxygen free radicals . J Mol Cell Cardiol 25 ( suppl II ): S 21, 1993 94. Bremer J , Greenberg DM : Methyl transfering enzyme system of microsomesin the biosynthesisoflecithin(phosphatidylcholine) . Biochim Biophys Acta 46 : 2054 16, 1961 95. HirataF'Axelmd J: Enzymaticmethylati ~ ~176176 increases erythrocyte membrane fluidity . Nature 275 : 219 - 220 , 1978 96. Mato JM , Alemany S : What is the function ofphospholipidN-methylation? Biochem J 213 : 1 - 10 , 1983 97. Ganguly PK , Panagia V , Okumura K , Dhalla NS : Activation of Ca2§ stimulatedATPaseby phospholipid N-methylation in cardiac sarcoplasmic reticulum . Biocbem Biophys Res Comm 130 : 472 - 478 , 1985 98. Panagia V , Okumura K , Makino N , Dhalla NS : Stimulation of Ca2§ pump in rat heart sarcolernmaby phosphatidylethanolamineN-methylation . Biochim Biophys Acta 856 : 383 - 387 , 1986 99. Panagia V , Makino N , Ganguly PK , Dhalla NS : Inhibition of Na§ 2§ exchangein heartsarcolemmalvesiclesby phosphatidylethanolamineNmethylation . Eur J Biochem 166 : 597 - 603 , 1987 100. StrittmatterWJ, HirataF, AxelrodJ: Phospholipidmethylationunmasks cryptic b-adrenergic receptors in rat reticulocytes . Science 204 : 1205 - 1207 , 1979 101. Kaneko M , Panagia V , Paolillo G , Majumder S , Ou C , Dhalla NS : InhibitionofcardiacphosphatidylethanolamineN-methylationby oxygen free radicals . Biochim Biophys Acta 1021 : 33 - 38 , 1990 102. Xie Z , WangY, Askari A , Huang WH , Klaunig JK , AskariA: Studies on the specificity of the effects of oxygen metabolites on cardiac sodium pump . J Mol Cell Cardiol 22 : 911 - 920 , 1990 103. TrumbleWR, Sutko JL , Reeves JP : ATP-dependentcalcium transport in cardiac sarcolemmal membrane vesicles . Life Sci 27 : 207 - 214 , 1980 104. Caroni P , Carafoli E : The Ca2§ ATPaseofheart sarcolemma . J Biol Chem 256 : 3263 - 3270 , 1981 105. Caroni P , Zurini M , Clark A : Transport ATPases . NY Acad Sci, New York 1982 , pp 403 - 420 106. Reeves JP , Bailey CA , Hale CC : Redox modification of sodium-calcium exchange activity in cardiac sarcolemmal vesicles . J Biol Cbem 261 : 4948 - 4955 , 1986 107. Shi ZQ , Davison AJ , Tibbits GF : Effects of active oxygen generated by DTT/Fe2§ on cardiac Na+-Ca2§ exchange and membrane permeability to Ca2+ . J Mol Cell Cardiol 21 : 1009 - 1016 , 1989 108. Kutryk MJB , Pierce GN : Stimulation of sodium-calcium exchange by cholesterol incorporation into isolated cardiac sarcolemmal vesicles . J Biol Chem 263 : 13167 - 13172 , 1988 109. Daly MJ , Elz JS , Nayler WG : Sarcolemmal enzymes and Na+-Ca2§ exchange in hypoxic, ischemic and reperfused rat hearts . Am J Physiol 247 : H237 - H243 , 1984 110. Meno H , Jannakani JM , Philipson KD : Effect of ischemia on sarcolemmal Na§ 2+ exchange in neonatal hearts . Am J Physiol 256 : HI615 - H1620 , 1989 111. Dixon IMC , Eyolfson DA , Dhalla NS : SarcolemmalNa+ -Ca2*exchange activity in hearts subjected to hypoxia reoxygenation . Am J Physio1253: HI026-HI034 , 1987 112. Bersohn MM , Philipson KD , Fukushima JY : Sodium-calciumexchange and sarcolemmal enzymes in ischemic rabbit hearts . Am J Physio1242: C288~2292 , 1982 113. Dixon IMC , Kaneko M , Hata T , Panagia V , Dhalla NS : Alterations in cardiacmembraneCaz+transportduringoxidativestress . Mol CellCardiol 99 : 125 - 133 , 1990 114. Kaneko M , Beamish RE , DhalIaNS: Depression ofhcart sarcolemmal Ca2+-pump activity by oxygen free radicals . Am J Physiol 256 : H368 - H374 , 1989 l 15. Kaneko M , Elimban V , Dhalla NS : Mechanism for depression of heart sarcolemmal Ca2+pump by oxygen free radicals . Am J Physiol 257 : H804 -HSI 1, t989 116. Salama G , Zaidi NF , Abramson JJ : Reactive disulfide compounds trigger Ca2. release from sarcoplasmic reticulum (SR) vesicles . Biophys J 53: 420 , 1988 117. Abramson JJ , Salama G : Critical sulfhydryls regulate calcium release from sarcoplasmic reticulum . J Bioenergetics Biomemb 21 : 283 - 294 , 1989 118. Abramson JJ , Cronin JR , Salama G : Oxidation induced by phthalocyanine dyes causes rapid calcium release from sarcoplasmic reticulum vesicles . Arch Biochem Biophys 263 : 245 - 255 , 1988 l 19. Abramson JJ , Buck E , Salama G , Casida JE , Pessah IN : Mechanism of anthraquinone-induced calcium release from skeletal muscle sarcoplasmic reticulum . J Biol Chem 263 : 18750 - 18758 , 1988 120. Zaidi NE Langenaur CF : Disulfide linkage of biotin identifies a 106- kDa Ca2 . release channel in sarcoplasmic reticulum . J Biol Chem 264 : 21737 - 21747 , 1989 121. YamadaS, lkemotoN: Distinctionofthiolsinvolvedinthespecific reaction steps ofthe Ca2+ -ATPaseof the sarcoplasmicreticulum . J Biol Chem 253 : 6801 ~ 807 , 1978 122. Yoshida H , TonomuraY: Chemical modification of the CaZ+-dependent ATPaseof sarcoplasmicreticulum from skeletalmuscle. I. BindingofNethylmaleimideto sarcoplasmicreticulum:Evidencefor sulfhydrylgroups in the active site of ATPase and for conformation changes induced by adenosine tri- and diphosphate . J Biochem 79 : 649 ~ 554 , 1976 123. Scherer NM , Deamer DW : Oxidative stress impairs the function ofsarcoplasmic reticulum by oxidation of sulfhydryl groups in the Ca2+-ATPase . Arch Biochem Biophys 246 : 589 - 601 , 1986 124. Steinberg H , Greenwald , RA , Moak SA , Das DK : The effect of oxygen adaptation on oxyradical injury to pulmonary endothelium . Am Rev Respir Dis 128 : 94 - 97 , 1983 125. Pierce GN , Ward R , Philipson KD : Role for sulfur containing groups in the sodium-calcium exchange of cardiac sarcolemmal vesicles . Memb Biol 94 : 217 - 225 , 1986 126. ZaidiNF, Lagenaur CF , Abrahamson JJ : Reactive disulfides trigger Ca2+ releason from sarcoplasmic reticulum via an oxidation reaction . J Biol Chem 264 : 21725 - 21736 , 1989 127. Garcia ML , KingVF, Siegel PKS , Reuben JP , Kagzorowski GJ : Binding of Ca2§entry blockersto cardiac sarcolemmalmembrane vesicles . J Biol Chem 261 : 8146 ~ 157 , 1986 i28. Grossmann H , Ferry DR , Goll A , Rombusch M : Molecular pharmacology ofthe calciumchannel:evidencefor subtypes,multipledrug-receptor sites, channel subunits, and the development ofa radioiodinated 1,4- dihydropyridine calcium channel label, [nSl] iodipine . J Cardiovasc Pharmacol 6 ( suppl 4): 608 - 621 , 1984 129. Hess ML , Okabe E , Kontos HA : Protonand free oxygen radical interaction with the calcium transport system of cardiac sarcoplasmic reticulum . J Mol Cell Cardiol 13 : 767 - 772 , 1981 130. Hess ML , Krause S , Kontos HA : Mediation of sarcoplasmic reticulum disruption in the ischemic myocardium: Proposed mechanism by the interaction of hydrogen ions and oxygen free radicals . Adv Exp Biol Med 161 : 377 - 387 , 1983 131. Okahe E , Hess ML , Oyama M , Ito H : Characterization of free radical mediated damage of canine sarcoplasmic reticulum . Arch Biochem Biophys 225 : 164 - 177 , 1983 132. HessML, OkabeE,AshP: Free radical mediation ofthe effects ofacidosis on calciumtransportby cardiacsarcoplasmicreticulumin whole heart homogenates . Cardiovasc Res 18 : 149 - 157 , 1984 133. Kukreja RC , Okabe E , Schrier G , Hess ML : Oxygen radical-mediated lipid peroxidation and inhibition of calcium ATPaseactivity of cardiac sarcoplasmic reticulum . Arch Biochem Biophs 261 : 447 - 475 , 1988 134. Okabe E , Odajima C , Taga R , Kukreja RC , Hess ML , Ito H : The effect of oxygen free radicals on calcium loading at steady state in canine sarcoplasmic reticulum . Mol Pharmaco134 : 388 - 394 , 1988 135. Kukreja RC , WeaverAB, Hess ML : Stimulatedhuman neutr0phils damage cardiac sarcoplasmic reticulum function by generation of oxidants . Biochim Biophys Acta 990 : 198 - 205 , 1989 136. Cumming DVE , Holmberg SRM , Kusama Y , Shattock M , Williams A : Effects of reactive oxygen species on the structure and function of the calcium-releasechannel isolatedfrom sheep cardiac sarcoplasmicreticulum . J Physio1420: 88P , 1990 137. Holmberg SRM , Cumming DVE , Kusama Y : Reactive oxygen species modify the structure and function of the cardiac sarcoplasmic reticulum calcium-release channel . Cardioscience 2 : 19 - 25 , 1991 138. Shttock MJ , Hearse DH , Matuura H : Ionic currents underlying oxidant stress-induced arrhythmias . In: J. Vereecke , P.P. Van Bogaert and E Verdonk (eds). Ionic currents and ischemia . Leuven University Press, Leuven, 1990 , pp 165 - 189 139. Burton KP , Morris AC , Massey KD , Buja M , Hagler HK : Free radicals alter ionic calcium levels and membrane phospholipids in cultured rat ventricular myocytes . J Mol Cell Cardiol 22 : 1035 - 1047 , 1990 140. Josephson RA , Silverman HS , Lakatta EG , Stem MD , Zweier JL : Study of the mechanisms of hydrogen peroxide and hydroxyl free radical-induced cellular injury and calcium overload in cardiac myocytes . J Biol Chem 266 : 2354 - 2361 , 1991 14l. Liu K , Massaeli H , Pierce GN : The action of oxidized low density lipoprotein on calcium transients in isolated rabbit cardiomyocytes . J Biol Chem 268 : 4145 - 4151 , 1993 142. Eley DW , Korecky B , Fliss H , Desilets M : Calcium homeostasis in rabbit ventricularmyocytes. Disruptionby hydrochlorous acid and restoration by dithiothreitol . Circ Res 69 : 1132 - 1138 , 1991


This is a preview of a remote PDF: http://link.springer.com/content/pdf/10.1007%2FBF00944207.pdf

Masanori Kaneko, Yuji Matsumoto, Hideharu Hayashi, Akira Kobayashi, Noboru Yamazaki. Oxygen free radicals and calcium homeostasis in the heart, Molecular and Cellular Biochemistry, 1994, 91-100, DOI: 10.1007/BF00944207