Kinetics and control of oxidative phosphorylation in rat liver mitochondria after chronic ethanol feeding

Abstract

Changes in the kinetics and regulation of oxidative phosphorylation were characterized in isolated rat liver mitochondria after 2 months of ethanol consumption. Mitochondrial energy metabolism was conceptually divided into three groups of reactions, either producing protonmotive force (∆p) (the respiratory subsystem) or consuming it (the phosphorylation subsystem and the proton leak). Manifestation of ethanol-induced mitochondrial malfunctioning of the respiratory subsystem was observed with various substrates ; the respiration rate in State 3 was inhibited by 27p4 % with succinate plus amytal, by 20p4 % with glutamate plus malate, and by 17p2 % with N,N,Nh,Nhtetramethyl-p-phenylenediamine\ascorbate. The inhibition of the respiratory activity correlated with the lower activities of cytochrome c oxidase, the bc " complex, and the ATP synthase in mitochondria of ethanol-fed rats. The block of reactions consuming the ∆p to produce ATP (the phosphorylating subsystem)

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