Application of modular kinetic analysis to mitochondrial oxidative phosphorylation in skeletal muscle of birds exposed to acute heat stress

We previously showed that heat stress stimulates reactive oxygen species (ROS) production in skeletal muscle mitochondria of birds, probably via an elevation in mitochondrial membrane potential (Delta Psi). To clarify the mechanism underlying the elevation of Delta Psi, modular kinetic analysis was applied to oxidative phosphorylation in skeletal muscle mitochondria of heat-stressed birds (34 degrees C for 12 h). In the birds exposed to heat stress, 'substrate oxidation' (a Delta Psi-producer) was increased compared to control (24 degrees C) birds, although there was little difference in 'proton leak' (a Delta Psi-consumer), suggesting that an elevation in the Delta Psi at state 4 may be due to enhanced substrate oxidation. It thus appears that enhanced substrate oxidation plays a crucial role in the overproduction of ROS for heat-stressed birds, probably via elevated Delta Psi. (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.