THE CHANGE OF THE FREE-ENERGY OF ATP HYDROLYSIS DURING GLOBAL-ISCHEMIA AND ANOXIA IN THE RAT-HEART - ITS POSSIBLE ROLE IN THE REGULATION OF TRANSSARCOLEMMAL SODIUM AND POTASSIUM GRADIENTS
THE CHANGE OF THE FREE-ENERGY OF ATP HYDROLYSIS DURING GLOBAL-ISCHEMIA AND ANOXIA IN THE RAT-HEART - ITS POSSIBLE ROLE IN THE REGULATION OF TRANSSARCOLEMMAL SODIUM AND POTASSIUM GRADIENTS
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DOI：
10.1016/s0022-2828(84)80015-2
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发表时间：
1984-01-01
影响因子：
5
通讯作者：
TERWELLE, HF
中科院分区：
文献类型：
--
作者：
FIOLET, JWT;BAARTSCHEER, A;TERWELLE, HF
The time course of change of the cytoplasmic free energy of ATP hydrolysis during acute global ischemia and during anoxic perfusion was determined in the isolated rat heart. The time course of change of transsarcolemmal Na+ and K+ gradients during anoxia, and of extracellular K+ during ischemia were measured. The free energy of ATP hydrolysis was calculated from the equilibrium of the creatine kinase reaction, taking into account the pH-dependence of the equilibrium constant, and intracellular inorganic phosphate. In control aerobic hearts of the mean free energy of ATP hydrolysis was 55.2 kJ/mol. Both during ischemia and anoxia it declines biphasically. The 1st rapid phase terminates within 4 min into a plateau of about 46 kJ/mol. The duration of this plateau is shorter during anoxia than during ischemia. The 2nd phase of decrease starts after 6-8 min during anoxia and after 15-20 min during ischemia. After 30 min of anoxia the free energy of ATP hydrolysis has decreased to 31 kJ/mol and after 30 min of ischemia a value of 35.5 kJ/mol is reached. The time courses of change of measured intracellular Na+ and K+ during anoxia and of extracellular K+ during ischemia were also biphasic. During anoxia the loss of intracellular K+ was almost equal to the gain of intracellular Na+ at any point. Based on the assumption that the Na+ pump is in thermodynamic equilibrium or near-equilibrium during anoxia and ischemia, the time courses of change of Na+ and K+ gradients during anoxia and of extracellular K+ during ischemia were calculated from the respective time courses of change of the free energy of ATP hydrolysis. Good agreement was observed between calculated and measured changes of Na+ and K+ gradients. The magnitude and direction of change of transsarcolemmal ion-gradients during anoxia and ischemia may be under direct thermodynamic control of myocardial energy metabolism.
