Metabolism of free fatty acids by myocardium and kidney

¹ Department of Physiology, Hahnemann Medical College, Philadelphia, Pennsylvania

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.

Key Words: gas chromatography of FFA • oxidation of individual FFA lipid metabolism • bicarbonate-C¹⁴ • heart-lipid • metabolism • kidney-lipid metabolism

Submitted on March 1, 1963