Laughlin M R, Heineman F W
Laboratory of Cardiac Energetics, NHLBI, NIH, Bethesda, MD.
J Mol Cell Cardiol. 1994 Dec;26(12):1525-36. doi: 10.1006/jmcc.1994.1173.
The effects of the cytosolic and mitochondrial redox state on the function and phosphorylation potential of working perfused rabbit hearts were studied. Hearts were perfused with glucose, while lactate, aminooxy-acetate (an inhibitor of the malate-aspartate shuttle), beta-hydroxybutyrate, and pyruvate were sequentially added to the perfusate to manipulate the cytosolic and mitochondrial NAD+/NADH ratio. The phosphorylation potential and product of ADP and P(i) were both found to be proportional to mitochondrial redox state. There was no overall relationship between cytosolic redox potential and the ATP/ADP x P(i) ratio, although at high mitochondrial NADH, there was a tendency for the states with more reduced cytoplasm to be associated with a lower phosphorylation potential. Cardiac output and dP/dt were decreased after 75 microM aminooxy-acetate was present for 15 min, and remained low when 0.5-1.0 mM beta-hydroxybutyrate was added, even though the beta-hydroxybutyrate period was characterized by both very low cytosolic NAD+/NADH and high mitochondrial NADH. Function returned to normal when the cytoplasm was oxidized by addition of 10 mM pyruvate, and although MVO2 rose from 4.0 +/- 0.4 to 5.0 +/- 0.5, this was not accompanied by statistical changes in either mitochondrial NADH or phosphorylation potential. Therefore, the cytosolic redox state may play a role in cardiac function, but has only a minor contribution to the regulation of the phosphorylation potential in the working perfused rabbit heart.
研究了细胞溶质和线粒体氧化还原状态对离体灌注工作兔心脏功能及磷酸化电位的影响。心脏用葡萄糖灌注，同时向灌注液中依次加入乳酸、氨基氧乙酸（苹果酸 - 天冬氨酸穿梭抑制剂）、β - 羟基丁酸和丙酮酸，以操纵细胞溶质和线粒体NAD⁺/NADH比值。发现磷酸化电位以及ADP与P(i)的乘积均与线粒体氧化还原状态成正比。细胞溶质氧化还原电位与ATP/ADP×P(i)比值之间不存在总体关系，尽管在高线粒体NADH水平时，细胞质还原程度更高的状态往往与较低的磷酸化电位相关。在75 microM氨基氧乙酸存在15分钟后，心输出量和dP/dt降低，并且当加入0.5 - 1.0 mMβ - 羟基丁酸时仍保持较低水平，尽管β - 羟基丁酸作用期间细胞溶质NAD⁺/NADH非常低且线粒体NADH很高。当通过加入10 mM丙酮酸使细胞质氧化时，功能恢复正常，并且尽管MVO₂从4.0±0.4升至5.0±0.5，但线粒体NADH或磷酸化电位均无统计学变化。因此，细胞溶质氧化还原状态可能在心脏功能中起作用，但对离体灌注工作兔心脏中磷酸化电位的调节作用较小。
