[Experimental study on metabolism of branched chain amino acids after partial hepatectomy].

Metabolism of branched chain amino acids (BCAA) after partial hepatectomy was investigated. Total amino acids of the plasma in the rats undergone 70% partial hepatectomy increased significantly as compared with those of control animals. This increase was due to an increase of sum of all amino acids other than BCAA, whereas total amount of BCAA was unaffected. Both BCAA aminotransferase (BCAA-AT) and branched chain ketoacid dehydrogenase (BCKA-DH), the rate limiting enzymes in BCAA metabolism, increased in mitochondria of the liver and BCAA-AT increased in skeletal muscle homogenate. These increases of both enzymes might reduce the concentration of BCAA relatively. Mitochondrial respiration such as state 3 respiration, respiratory control index (RCI) and ATP synthesis in mitochondria of regenerating liver increased remarkably, when not only succinate but also alpha-ketoisocaproic acid was used as a substrate. ATP synthesis, however, was much higher and mitochondrial respiration was more coupled when alpha-ketoisocaproic acid was used as a substrate. These results suggest that BCAA metabolism was activated after partial hepatectomy and BCAA might serve as an appropriate substrate for regenerating liver.