Study of the role of essential fatty acids in liver metabolism.

The high concentration of lipide material in mitochondria (l-3) suggests that the enzyme activity in the mitochondria may be particularly associated with the presence of lipide. Burr and Beber (4) have reported that animals fed a fat-deficient diet possess a significantly higher metabolic rate than comparable controls. In previous studies of the rale of essential fatty acids in metabolism, Kunkel and Williams (5) found that both cytochrome oxidase and endogenous respiration of the livers of fat-deficient rats were significantly higher than normal, although succinoxidase was unaffected by the deficiency. Recently Klein and Johnson (6) reported that liver mitochondria from fat-deficient rats esterify less high energy phosphate per mole of oxygen taken up during the oxidation of certain intermediates of the tricarboxylic acid cycle. It was suggested that the uncoupling of oxidative phosphorylation in essential fatty acid (EFA)’ deficiency is restricted to a certain step in the electron transport system, at or near the level of DPN reduction or oxidation. Uncoupled phosphorylation (7) could thus account for the high metabolic rate (4), the high endogenous respiration, and the high cytochrome oxidase of EFA-deficient rats (5). Tulpule and Patwardhan (8) have observed a reduction in liver glutamic dehydrogenase activity of EFA or vitamin Be-deficient rats, which was further decreased by a double deficiency of these dietary factors. On the other hand succinic and butyric dehydrogenase activities, as measured by methylene blue reduction, were unaffected by a vitamin Be deficiency; however, EFA or EFA plus vitamin Be deficiencies caused some reduction in these dehydrogenases.