The influence of intravenous medium- and long-chain triglycerides and carnitine on the excretion of dicarboxylic acids.

Four groups of male Wistar rats were alimented parenterally for 3 days. Groups 1 and 2 received medium-chain triglycerides (MCT) and groups 3 and 4 long-chain triglycerides (LCT). Groups 2 and 4 were supplemented with 100 mg L-carnitine/kg/day. The MCT-alimented rats presented with a distinct excretion of the dicarboxylic acids: adipic acid (C6), suberic acid (C8), and sebacic acid (C10). The acids excreted corresponded to the infused pattern of monocarboxylic acids: caproic acid (C6), caprylic acid (C8), and capric acid (C10). Dicarboxylic acid excretion after MCT administration may reflect an insufficient capacity of beta-oxidation on one hand or a preferential omega-oxidation of medium-chain fatty acids on the other. Carnitine supplementation lead to a further increase of the dicarboxylic acids in the MCT-group. beta-OH-butyric acid excretion decreased after carnitine in the MCT as well as in the LCT group. An increased transport of fatty acid-carnitine compounds out of the mitochondria is discussed as an important effect of carnitine supplementation. Hereby medium-chain fatty acids may be more accessible for omega-oxidation.