Distribution and Gradient of Lactate Between Blood and Heart Muscle.

Abstract

Summary The concept that blood lactate is in equilibrium with myocardial concentrations of this substrate could not be demonstrated in the anesthetized dog. A factor questioning the existence of an equilibrium was the distribution of lactate found in the walls of the heart. Levels in right and left atria were markedly different from those found in the base, midportion and apex of the right and left ventricles. Although administration of sodium lactate by vein raised arterial lactate almost 6 times control, right and left ventricular muscle concentrations remained unchanged. The linear relationship observed between the duration of myocardial anoxia and lactate production by cardiac muscle made possible the calculation of the in vivo myocardial lactate level, a value significantly higher than the level present in arterial blood. The entry of lactate into the myocardial cell may therefore be governed by a mechanism of active transport rather than simple diffusion.