Action of carnitine on long chain fatty acid oxidation by liver

The addition of dl-carnitine to various types of particulate liver preparations resulted in augmented oxidation of labeled palmitate and stearate. In contrast, carnitine exerted little if any effects upon the degradation of octanoate or laurate. The oxidation of palmityl-1-C14 CoA by liver particulates was not affected by the presence of carnitine, suggesting that carnitine action is at a stage prior to the formation of this intermediate. Since carnitine addition consistently induced an increase in long chain fatty acid oxidation by slices and by subcellular particulates but did not enhance fatty acid degradation by various soluble systems, it was concluded that an intracellular structure is probably required for carnitine action. A carnitine effect on the long chain fatty acid activating enzyme could not be demonstrated. It was concluded tentatively that the site of carnitine action is independent of direct influence on the known enzymes required for fatty acid oxidation. Palmitic acid oxidation by particulate preparations was inhibited by added serum albumin or calcium, and this inhibition was in large part relieved by the addition of carnitine.