Effects of endosulfan on bioenergetic properties of skeletal muscle mitochondria from the freshwater catfish (Clarias batrachus)

Abstract

The effects of a sublethal concentration of an organochlorine pesticide endosulfan on fish skeletal muscle mitochondria oxidizing isocitrate and succinate in vivo and in vitro were investigated. The endosulfan depressed significantly State 3 rates and RCR with succinate, whereas it prevented completely the oxidation of isocitrate. The CCCP-uncoupled rates and State 4 rates of succinate oxidation remained unaffected by endosulfan. The activity of masked ATPase was significantly increased in presence of endosulfan. There was a progressive stimulatory effect of endosulfan on mitochondrial ATPase. The skeletal muscle fibres of endosulfan exposed fish undergo ultrastructural changes that are characterized by deformation of the myofibrils and disappearance of mitochondria. Summarizing, it can be stated that endosulfan exerts an inhibitory effect on electron transport and affects ATP synthetase complex leading to an impairment in mitochondrial bioenergetics, which can be correlated with marked ultrastructural alterations in the skeletal muscle fibres of the fish. © 1995.