Morgan H E, Chua B H, Siehl D, Kira Y, Kochel P J, Gordon E E
Fed Proc. 1986 Oct;45(11):2563-7.
Induction of cardiac work increased protein synthesis in hearts supplied glucose or a mixture simulating normal plasma levels of glucose, insulin, glucagon, lactate, and beta-hydroxybutyrate. During 2 h of perfusion, cardiac work did not accelerate protein synthesis in hearts supplied a mixture of glucose, lactate, and higher concentrations of insulin. Protein degradation was decreased by work in hearts supplied glucose. Nitrogen balance was negative in Langendorff-perfused hearts provided glucose, but was less so in working preparations. Nitrogen balance was zero or positive in working hearts provided the mixture simulating plasma or the mixture of glucose, lactate, and insulin. In Langendorff preparations, increased aortic pressure accelerated protein synthesis during the second hour of perfusion in hearts supplied glucose, glucose plus insulin, or pyruvate. When ventricular pressure development was prevented by ventricular draining or when drained hearts were arrested with tetrodotoxin, protein synthesis still increased as perfusion pressure was raised from 60 to 120 mm Hg. Oxygen consumption increased as aortic pressure was increased in drained, beating hearts, but was unaffected in arrested, drained hearts. These studies indicated that increased aortic pressure and its attendant stretch of the ventricular wall were the mechanical parameter most closely associated with faster rates of protein synthesis.
心脏工作负荷的增加会提高接受葡萄糖或模拟正常血浆水平的葡萄糖、胰岛素、胰高血糖素、乳酸和β-羟基丁酸混合物灌注的心脏中的蛋白质合成。在灌注2小时期间，心脏工作负荷并未加速接受葡萄糖、乳酸和更高浓度胰岛素混合物灌注的心脏中的蛋白质合成。在接受葡萄糖灌注的心脏中，工作负荷可减少蛋白质降解。在Langendorff灌注的心脏中，若提供葡萄糖，氮平衡为负，但在工作状态的心脏中，氮平衡的负值较小。在接受模拟血浆的混合物或葡萄糖、乳酸和胰岛素混合物灌注的工作心脏中，氮平衡为零或正值。在Langendorff制备中，在接受葡萄糖、葡萄糖加胰岛素或丙酮酸灌注的心脏中，灌注第二小时时主动脉压力升高会加速蛋白质合成。当通过心室引流阻止心室压力升高，或当引流的心脏用河豚毒素停跳时，随着灌注压力从60毫米汞柱升至120毫米汞柱，蛋白质合成仍会增加。在引流的跳动心脏中，随着主动脉压力升高，耗氧量增加，但在停跳的引流心脏中，耗氧量不受影响。这些研究表明，主动脉压力升高及其伴随的心室壁拉伸是与更快的蛋白质合成速率最密切相关的机械参数。
