METABOLISM OF CARDIAC MUSCLE: UTILIZATION OF C14 LABELLED PYRUVATE AND ACETATE BY RAT HEART SLICES

Abstract

Factors affecting the measurement of respiration of rat ventricle slices are discussed. Measurements of the utilization of labelled pyruvate by rat ventricle slices indicate that, of the total amt. of pyruvate which disappears, approx. 69% is oxidized to CO2, 20% is reduced to lactate and less than 1% is incorporated into tissue fat and protein. Labelled acetate added alone is readily oxidized to CO2 by rat ventricle and accounts for 40 to 60% of the O2 consumption. When pyruvate and acetate are added together both are metabolized but the O2 consumption is the same as with pyruvate alone. The conversion of acetate to CO2 in the presence of pyruvate is less than half that observed when acetate was the only added substrate.