Cytochrome oxidase status in protein-energy-deficient rats.
Effects of changes in dietary protein have been investigated on three mitochondrial enzymes, succinate dehydrogenase, isocitrate dehydrogenase and cytochrome oxidase. Weanling rats (21 days old) were fed for 30 days on (a) a commercially produced diet (CPD) containing 21.0% dietary protein and (b) a low protein-high carbohydrate diet (LPD) containing 3.47% dietary protein. Signs of protein-energy malnutrition developed in the animals having the low protein diet. The mitochondrial enzymes were assayed. Some of the experimental rats were repleted by feeding them on a protein-rich diet for 3 weeks, and the same mitochondrial enzymes were assayed. The activity of mitochondrial cytochrome oxidase, which fell to 24% of the control values during the period of deficiency, rose to 91% of the values for control rats during rehabilitation. The activities of succinate dehydrogenase and NAD+-isocitrate dehydrogenase fell to 75 and 73% of the control values, respectively, during depletion and rose to 83 and 88% during repletion in line with the general rate of recovery of the malnourished rats as reflected by the changes in the body weights during repletion. These results show that mitochondrial cytochrome oxidase is very sensitive to changes in dietary protein. Its activity drops sharply with reduction in dietary protein intake and rises rapidly, outstripping the rate of general recovery on reverting to a protein-rich diet.
D000818:Animals; D001835:Body Weight; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D009929:Organ Size; D010088:Oxidoreductases / Q000378:metabolism*; D011502:Protein-Energy Malnutrition / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013385:Succinate Dehydrogenase / Q000378:metabolism
D010088:Oxidoreductases; D007521:Isocitrate Dehydrogenase; D013385:Succinate Dehydrogenase; D003576:Electron Transport Complex IV