The regulation of glycerol 3-phosphate oxidase of rat brownadipose tissue mitochondria by long-chain free fatty acids

Abstract

Added free fatty acids inhibit oxidation of glycerol 3-phosphate, succinate and NADH in brownadipose tissue mitochondria from 10-day-old rats. The most pronounced is the inhibitory effect on glycerol 3-phosphate cytochromec reductase (GP-cyto.c reductase). Contrary to other reductases, GP-cyto.c reductase activity of freshly isolated mitochondria is already inhibited by the fraction of endogenous free fatty acids. Both added and endogenous free fatty acids inhibition of GP-cyto.c reductase is fully reversible by the removal of free fatty acids by bovine serum albumine treatment. The inhibition of GP-cyto.c reductase is of strictly non-competitive type. The most inhibitory are unsaturated long-chain free fatty acids — oleic and linoleic acid. Results are discussed with regards to the regulatory importance of free fatty acids in brown-adipose tissue during intensive non-shivering thermogenesis.