Effect of varying protein contents of the feed on the concentration of metabolites nad nadh redox states and enzyme activities in the liver of rat
Jansen, R.; Reichl, J.R.
Zeitschrift fuer Ernaehrungswissenschaft 19(1): 57-65
1980
Accession: 005281606
Rats (36) were divided into 4 groups and consequently fed 16 days ad lib with 1 of 4 feed rations varying in protein contents. Final weights and weight gains of rats increased from 97.7 .+-. 2.9 and 3.81 .+-. 0.16 g/ day by the protein poor group to 125.6 .+-. 2.6 g and 5.33 .+-. 0.10 g/ day by the protein rich group of animals, respectively. Daily intakes of the dry matter and fat were similar in all animal groups; daily intakes of the protein and of the carbohydrates were significantly different within all 4 animal groups. Metabolites (18) were determined in the livers of 4 rats per each group of animals; certain parallels were detected between their concentrations in liver and the contents of protein in feed. An equally directed tendency to the protein content of feed was found by concentration of glycerophosphate, PYR [pyruvate] and AMP, a reverse tendency by concentration of fructose-1,6-diphosphate, dihydroxyacetone phosphate, BHBA [.beta.-hydroxybutyrate] and partly by aspartate. Only some of these tendencies were statistically significant. Concentrations of malate and glucose sank first with decreasing protein content of feed and rose again by the continued decrease of protein in feed. Concentration of acetyl Coenzyme A and ACAC [acetoacetate] behaved contrary to this tendency. NAD+/NADH-redox states calculated from concentration of ACAC and BHBA showed the same tendency as the concentration of ACAC in liver. These redox states calculated for liver mitochondria as well as redox states calculated from concentrations of PYR and lactate for liver cytosol showed lowest values by the protein poor group D of animals. The same was found in the liver for ratio of ATP/AMP and for energy load expressed as (ATP + 1/2 ADP)/(ATP + ADP + AMP). Activities of lactate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase increased with decreasing protein content of feed. Group D was significantly different from the other animal groups. Activity of glutamate dehydrogenase decreased with decreasing content of protein feed. Glucose-6-phosphate dehydrogenase was not affected.