Okuda M, Lee H C, Chance B, Kumar C
Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia 19104-6089.
Circ Shock. 1992 Jul;37(3):209-19.
The influx of extracellular Ca2+ has been postulated to be one of the mediators of ischemia-reperfusion injury. A possible link between Ca2+ influx and oxygen radical generation has also been suggested. In the present study, using the isolated perfused rat liver, we evaluated the role of extracellular Ca2+ on oxygen radical generation, liver damage, and lipid peroxidation during 30 min ischemia and 60 min of reperfusion. Oxygen radical generation in the liver was continuously monitored by lucigenin-enhanced chemiluminescence. Liver damage and lipid peroxidation were evaluated by measuring lactate dehydrogenase (LDH) and thiobarbituric acid reactive substances (TBARS) release into the effusate, respectively. In the absence of extracellular Ca2+ (much less than 30 microM) oxygen radical generation from the liver increased gradually over 2 hr and there were concomitant increases in LDH and TBARS release. When livers were made ischemic and then reperfused, oxygen radical generation increased at the onset of reperfusion and then decreased over 30 min of reperfusion. After 30 min of reperfusion, livers reperfused with low Ca2+ buffer showed a linear increase in oxygen radical generation as well as progressive increases in LDH and TBARS release. On the other hand, livers reperfused with Ca2+ containing (1.25 mM) buffer showed no further increase in oxygen radical generation and no evidence of progressive liver damage and lipid peroxidation. These results suggest that Ca2+ overload is not a primary cause of liver ischemia-reperfusion injury and that the presence of extracellular Ca2+ during reperfusion is necessary to maintain normal liver function.
细胞外钙离子内流被认为是缺血再灌注损伤的介质之一。钙离子内流与氧自由基生成之间的可能联系也已被提出。在本研究中，我们使用离体灌注大鼠肝脏，评估了细胞外钙离子在30分钟缺血和60分钟再灌注期间对氧自由基生成、肝损伤和脂质过氧化的作用。通过光泽精增强化学发光法持续监测肝脏中的氧自由基生成。分别通过测量释放到流出液中的乳酸脱氢酶（LDH）和硫代巴比妥酸反应性物质（TBARS）来评估肝损伤和脂质过氧化。在无细胞外钙离子（远低于30微摩尔）的情况下，肝脏中的氧自由基生成在2小时内逐渐增加，同时LDH和TBARS释放也随之增加。当肝脏进行缺血然后再灌注时，氧自由基生成在再灌注开始时增加，然后在30分钟的再灌注过程中下降。再灌注30分钟后，用低钙缓冲液再灌注的肝脏显示氧自由基生成呈线性增加，同时LDH和TBARS释放也逐渐增加。另一方面，用含1.25毫摩尔钙离子的缓冲液再灌注的肝脏未显示氧自由基生成进一步增加，也没有进行性肝损伤和脂质过氧化的迹象。这些结果表明，钙离子超载不是肝脏缺血再灌注损伤的主要原因，并且再灌注期间细胞外钙离子的存在对于维持正常肝功能是必要的。
