Anaerobic Metabolism of Heart

Abstract

Calculation of excess lactate removal and production, together with the arteriovenous difference of oxygen and carbon dioxide content of the coronary circulation, was performed during normal ventilation, induced hypoxia, and apnea in dogs. During ventilation with 100 per cent oxygen or room air, excess lactate was removed by the canine heart and continued to be removed until the arterial oxygen content fell to an average level of 9 ml./100 ml. of arterial blood. Below this level, excess lactate was produced by the heart, indicating a shift to anaerobic metabolism. The heart continued to work anaerobically, and its efficiency was increased since little, if any, oxygen was utilized. During severe hypoxia, the oxygen equivalent of the excess lactate produced was equal to the carbon dioxide produced. The heart, still performing work, was functioning completely anaerobically.