[Effect of sodium and potassium on cardiac infarct in rats].

During the induction of myocardial infarction in the rat by isoproterenol, a decrease in the voltage of the T wave in the electrocardiogram is produced, which reflects myocardial ischemia through a previous infusion of a KCl solution; while the perfusion of NaCl increases the voltage of such wave and therefore cardiac ischemia. The values of free Pi in the myocardium increase significantly with the administration of isoproterenol. If KCl has been perfused previously, the figures of free Pi are superior in 155% of those obtained with the perfusion of NaCl. The values of all the energetic phosphates, AMP, ADP and ATP decrease inversely and in a significant way with isoproterenol and the perfusion of NaCl and KCl. The activity of creatine-phosphokinase in the myocardium decreases with isoproterenol, specially with the previous perfusion of KCl Similarly, the activity of the isoenzimes of lactic dehydrogenase L1 and L2 (alpha-HBDH), decreases, which intensifies with previous perfusion of NaCl, but diminishes with KCl. The activity of malicodehydrogenase (MDH) in the myocardium decreases with isoproterenol, even with the previous perfusion of NaCl, but in lesser degree than with KCl.