Quaife R A, Kohmoto O, Barry W H
Cardiology Division, University of Utah Medical Center, Salt Lake City, Salt Lake City 84132.
Circulation. 1991 Feb;83(2):566-77. doi: 10.1161/01.cir.83.2.566.
To investigate factors contributing to reperfusion and reoxygenation myocardial injury, we exposed layers of cultured chick ventricular myocytes to severe hypoxia for up to 3 hours in the presence of 20 mM 2-deoxyglucose, zero glucose, and 5 mM pyruvate, and then exposed the myocytes to reoxygenation. Lactate dehydrogenase (LDH) release was moderately increased during 3 hours of hypoxia but was increased markedly during reoxygenation. Coincident changes in intracellular calcium concentration ([Ca2+]i) and cell motion were also measured during hypoxia and reoxygenation. During hypoxia, [Ca2+]i increased to more than 1 microM, and with reoxygenation, [Ca2+]i abruptly decreased slightly but remained elevated more than 1 microM. Cells developed a stable rigor after 30 minutes of hypoxia. Reoxygenation caused a marked hypercontracture within 5 minutes. Pretreatment of myocytes with either 2,3-butanedione monoxime, which inhibits Ca2(+)-dependent force development, or cyanide inhibited reoxygenation hypercontracture. LDH release after reoxygenation was also significantly reduced in the presence of 2,3-butanedione monoxime. Treatment of myocytes with superoxide dismutase and catalase during hypoxia also resulted in a decrease in LDH release during reoxygenation. We conclude that an abrupt increase in [Ca2+]i during reoxygenation does not account for reoxygenation injury. However, in the presence of elevated [Ca2+]i, reoxygenation and the resulting probable resynthesis of ATP causes [Ca2+]i-dependent myofilament crossbridge cycling, and the resulting hypercontracture contributes to myocyte damage. The generation of oxygen free radicals after reoxygenation also appears to contribute to cell injury in this system.
为了研究导致再灌注和再氧合心肌损伤的因素，我们将培养的鸡心室肌细胞层在20 mM 2-脱氧葡萄糖、零葡萄糖和5 mM丙酮酸存在的情况下暴露于严重缺氧环境中长达3小时，然后使肌细胞进行再氧合。在缺氧3小时期间，乳酸脱氢酶（LDH）释放适度增加，但在再氧合期间显著增加。在缺氧和再氧合期间还测量了细胞内钙浓度（[Ca2+]i）和细胞运动的相应变化。在缺氧期间，[Ca2+]i增加到超过1微摩尔，而再氧合时，[Ca2+]i突然略有下降，但仍保持在超过1微摩尔的水平。缺氧30分钟后细胞出现稳定的强直收缩。再氧合在5分钟内导致明显的超收缩。用抑制Ca2(+)-依赖性力产生的2,3-丁二酮单肟或氰化物预处理肌细胞可抑制再氧合超收缩。在存在2,3-丁二酮单肟的情况下，再氧合后的LDH释放也显著减少。在缺氧期间用超氧化物歧化酶和过氧化氢酶处理肌细胞也导致再氧合期间LDH释放减少。我们得出结论，再氧合期间[Ca2+]i的突然增加不能解释再氧合损伤。然而，在[Ca2+]i升高的情况下，再氧合以及由此可能产生的ATP再合成会导致[Ca2+]i依赖性的肌丝横桥循环，而由此产生的超收缩会导致心肌细胞损伤。再氧合后氧自由基的产生似乎也导致了该系统中的细胞损伤。
