The enzymatic activities of branched-chain amino acid catabolism in tumour-bearing rats.

Rats bearing the Walker-256 carcinosarcoma showed significant changes in branched-chain amino acid metabolism as compared with their non-tumour-bearing controls. In vitro measurement of branched-chain amino acid transaminase and branched-chain 2-oxo acid dehydrogenase showed significant increases in the skeletal muscle of tumour-bearing animals. In addition, the circulating concentration of leucine was increased in the tumour-bearing group. It can be concluded that the metabolism of branched-chain amino acids in the host is profoundly altered by the presence of a tumour and this may well be one of the main factors contributing to the so-called cancer cachexia.