ACTIVITY OF SOME RESPIRATORY ENZYMES AND CYTOCHROME CONTENTS IN RAT HEPATIC MITOCHONDRIA FOLLOWING AFLATOXIN B-1 ADMINISTRATION

Effects of aflatoxin B-1 (AFB(1)) administration (7 mg/kg body weight, i.p.) on rat hepatic mitochondrial respiratory components have been e xamined. Succinoxidase and cytochrome oxidase activities were decrease d in liver mitochondria isolated from rats 12-24 h after AFB(1) treatm ent. Both enzyme activities returned to normal levels after 48 h. Glut amate dehydrogenase and beta-hydroxybutyrate dehydrogenase activities did not show any alterations up to 24 h and thereafter increased at 48 -72 h. Succinate dehydrogenase activity was impaired by 41% at 12 h an d thereafter was found to be normal. The intramitochondrial cytochrome b content declined at 24-72 h, whereas cytochrome aa(3) content was d ecreased maximally at 72 h after AFB(1) administration. These observat ions on mitochondrial enzyme activities and cytochrome contents correl ate well with our earlier observations made on hepatic mitochondrial r espiratory rates after AFB(1) treatment. The impairment of respiratory functions possibly results from membrane damage and selective modific ation of gene expression in mitochondria imparted by AFB(1).