Effect of ketone bodies on cardiac metabolism

Abstract

The effect of acetoacetate infusion on myocardial metabolism was studied in 13 dogs at varying concentrations of acetoacetate. Acetoacetate was extracted by the myocardium at arterial levels of from 1 to 54 mg/100 ml. At arterial levels of above 60 mg/100 ml, extraction of acetoacetate by the heart was very small. Considerable amounts of the infused acetoacetate were reduced to beta-hydroxybutyrate. Acetoacetate inhibited the utilization of free fatty acids by the heart, resulting in a rise in the respiratory quotient of the heart. An increase in the myocardial extraction of lactate occurred at arterial acetoacetate levels of below 34 mg/100 ml. Between 34 and 80 mg/100 ml of acetoacetate levels, myocardial lactate extraction declined; the ketone became the preferred fuel of the myocardium at arterial acetoacetate levels between 34 and 54 mg/100 ml. Arterial glucose levels fell gradually during the experiment, leading to severe hypoglycemia. The negative myocardial balance of pyruvate significantly increased throughout the experiment. Coronary blood flow, heart rate, left ventricular pressure, myocardial contractility, and EKG were not affected significantly by arterial acetoacetate levels ranging from 1 to 80 mg/100 ml.