Changes in bioenergetics of skeletal muscle mitochondria during experimental trichinosis in rats

Abstract

Changes in bioenergetics were studied in mitochondria isolated from skeletal muscles of rats in the course of experimental trichinosis. In fortified media supporting oxidative phosphorylation, oxygen uptake with succinate was greatly enhanced, while the oxidation of glutamate and of malate plus pyruvate was manifold inhibited. The protective effect of BSA added was negligible in this case. The efficiency of oxidative phosphorylation coupled to the oxidation of all substrates examined was strongly inhibited in the course of experimental trichinosis, the inhibition being to a high extent removed by the addition of 0.5% bovine serum albumin to the incubation medium. The observed changes were interpreted as a two-stage phenomenon: (1) the early acute process resulting in the uncoupling of oxidative phosphorylation easily reversed by BSA and in a drop in the rate of oxidation of substrates mediated via NAD; (2) the later, secondary process characterized by the same phenomena but more pronounced and less reversible by BSA, accompanied by almost twofold increase in succinate oxidation. In in vitro experiments, a cytoplasmic fraction of Trichinella spiralis larvae was added to phosphorylating mitochondria isolated from rat muscle. A strong inhibition of oxidation of glutamate and of pyruvate plus malate was obtained while the oxidation of succinate was stimulated. With all substrates oxidative phosphorylation was highly uncoupled. The factor responsible for the uncoupling was sensitive to high temperature, but resistant to a 24-hr dialysis.