[Thyroid hormones and mitochondrial cytochrome c oxidoreductase activity]

In the experiments on albino male rats it was shown that thyroid hormones, exerting organospecific effect, control both the activity and the amount of cytochrome-c-oxidoreductase in hepatic, renal, cardiac and cerebral mitochondria. In the mechanism of cytochrome-c-oxidoreductase regulation thyroxin effect is likely to be mediated by cytochrome c amount. Supraphysiological thyroxin concentrations exert a direct action on the enzyme, whereas its physiological levels regulate cytochrome-c-oxidase, acting as an inductor.