Effects of metabolic acidosis and alkalosis on coronary blood flow and myocardial metabolism in the intact dog

Abstract

Severe metabolic acidosis and alkalosis were induced in anesthetized dogs by the infusion of solutions of hydrochloric acid and sodium bicarbonate. Infusions of sodium chloride were administered to other dogs under the same experimental circumstances. Measurements were made of arterial blood pressure, heart rate, cardiac output and coronary blood flow, arterial blood pH, and the content of oxygen, total CO2, lactate, pyruvate and glucose in both arterial and coronary venous blood. The cardiac output and coronary blood flow were decreased by acidosis and increased by alkalosis, the changes induced by alkalosis. There were no significant changes of left ventricular efficiency. Acidosis increased blood glucose concentrations and interfered with the increased myocardial uptake of glucose expected at higher arterial glucose levels. Alkalosis increased blood lactate and pyruvate levels and, correspondingly, the myocardial uptake of these carbohydrate substrates. It is concluded that cardiac dynamic function (as indicated by measurements of cardiac efficiency and output and arterial pressure) is much less affected by severe metabolic acidosis in the intact animal than in the isolated perfused organ.