Oxidative phosphorylation in mitochondria isolated from stressed rat heart

Oxidative phosphorylation was measured polarographically in mitochondria isolated from rat heart. With regard to ADP/O ratio and respiratory control index, no differences were found among mitochondria isolated from normal, acutely (increased pneumatic resistance of the heart-lung preparation) and chronicly (renal hypertension) stressed heart. However, the acute stressed heart induced by strangulating the outflow tract of the heart-lung preparation showed clear depression and tendency to depression, respectively, in the level of ADP/O ratio and respiratory control index in mitochondria. The results indicate that there is no change in the oxidative phosphorylating mechanism of the myocardial mitochondria of nonfailed heart despite acute or chronic pressure loadings; however, there is an uncoupling of oxidative phosphorylation in mitochondria of the failed heart after acute strangulation of the outflow tract.