Electrolyte Alterations in Acute Myocardial Ischemic Injury.

• Most investigations of the electrolyte shifts occurring in injured myocardial cells have been made by direct analysis of excised ischemic tissue obtained from myocardial infarcts. These studies have shown that significant shifts in the electrolytes of ischemic myocardial cells do not occur until about 60 minutes after the time the cells are known to be irreversibly injured. This 60-minute period could be a characteristic of the manner in which the dying myocardial cell comes into equilibrium with its environment; or, the process of equilibrium could be prolonged because diffusion of electrolyte within the infarct is slowed by the permanently reduced arterial blood flow. The studies described in this paper were made on myocardial cells irreversibly injured by a transient period of ischemia and the findings are contrasted to those noted in the permanent ischemia system used previously. Results show that only a brief period of restored flow of arterial blood to the ischemic myocardium is required to induce the massive electrolyte shifts characteristic of dead myocardial cells.