Metabolism of free fatty acids by myocardium and kidney

Abstract

The myocardial and renal removal and oxidation of plasma free fatty acids (FFA) were studied in dogs receiving an infusion of I-C14-palmitate, oleate, linoleate, or octanoate. The myocardium extracted about 40% of the total arterial FFA, and some was oxidized to CO2. Blood C14O2 was consistently higher in the coronary sinus than in the artery. The specific activity of the coronary sinus C14O2 was higher than that of the arterial C14O2 in dogs infused with long-chain fatty acids. The specific activity of arterial C14O2 was higher than that of the coronary sinus C14O2 when octanoate was infused. There were no differences observed in FFA extraction and C14O2 production among the different groups of animals receiving the various long-chain fatty acids. In gas chromatographic studies palmitic acid was the only FFA with a consistent net removal by the kidney. Approximately 9% of the arterial radiopalmitate was removed by this organ in dogs receiving infusions of palmitic acid-1-C14. Simultaneously, C14O2 was produced by the kidney. A consistent removal of oleate-1-C14 or a significant production of C14O2 was not found. Infusion of octanoate-1-C14 led to a marked release of C14O2 by the kidney, with greatly increased CO2 specific activity in the renal vein.