TIME-COURSE OF OXIDATIVE-PHOSPHORYLATION IN LIVER-MITOCHONDRIA OF CHICKENS FED ON HIGH-PROTEIN DIET

1. Progressive alterations in oxidative phosphorylation of liver mitoc hondria were followed for 14 d in growing chickens fed on either semi- purified low (7%) or high (61%) protein-energy diet. Hepatic mitochond rial oxidative phosphorylation rates were assessed polarographically w ith pyruvate + malate as substrates. 2. The ADP:O values were reduced significantly dr d after the feeding of a high-protein-energy diet, wh en compared with those in chickens fed on a low-protein-energy diet, w hereas the state 3 oxidation rates in chickens fed on a high-protein-e nergy diet from day 6 to 14 were significantly lower than those in low -protein-fed chickens. 3. No changes in sensitivity of mitochondrial A TPase activity to oligomycin, expressed as % of total ATPase activity, were observed among chickens fed for 21 d on diets with various prote in concentrations though the F0F1-ATPase activity, expressed per mg pr otein, tended to decrease in chickens fed on high-protein-energy diet. 4. These results suggest that the reduced ADP:O values for liver mito chondria in the high-protein-fed chickens may not be involved in the d egrees of integrity of the F0F1-ATPase.