Effect of ketones on metabolism of FFA by dog myocardium and skeletal muscle in vivo.

LITTLE, JOHN R., MASAI-URO GOTO, AND JOHN J. SPITZER. E$ect of ketones on metabolism of FFA by dog myocurdium and skeletal muscle in Go. Am. J. Physiol. 219(5): 1458-1463. 1970.-The uptake of P-hydroxybutyrate (p-OHB), acetoacetate (AcAc), and free fatty acids (FFA) by the myocardium and the thigh skeIeta1 muscle of mongrel dogs was measured under control conditions and during the infusion of Na dl-/3-hydroxybutyrate. Oxidation of FFA was also determined by continuously infusing palmitate-l -14C complexed to human albumin during each experiment and measuring the FFA-14C uptake and the CO2 and 14C02 production. Infusion of the exogenous ketone caused an elevation in the blood levels of both P-OHB and AcAc. A marked uptake of P-OHB and AcAc by myocardium and skeletal muscle was observed, and this was accompanied by a decrease in the rate of FFA uptake and oxidation by both tissues. The specific activity of FFA-14C was lower in the venous bXood from both tissues than in the arterial blood, indicating release of unlabeled FFA. A small but significant uptake of triglyceride-14C by both tissues was observed. Under the present experimental conditions ketones appeared to be the major substrate for the myocardium; if completely oxidized they could have accounted for 83y0 of the myocardial CO2 production.