THE ACTIVITY OF BRANCHED-CHAIN ALPHA-KETO ACID DEHYDROGENASE COMPLEX IN RAT DIGESTIVE TRACTS - EFFECTS OF DIETARY-PROTEIN AND EXERCISE

Branched-chain alpha-keto acid dehydrogenase complex is the rate Limit ing enzyme in catabolism of branched-chain amino acids. In this study, we examined effects of dietary protein and exercise on the complex ac tivity in digestive tracts (stomach, small intestine and colon) of rat s. Rats were fed a high (30%) or low (8%) protein diet for 3 weeks and a half of rats in each diet group was exercised by 85 min running jus t prior to sacrifice on the final day of the experiment. Total and act ual (active form) activities of the complex were markedly high in stom ach compared to other two tissues and the actual activity in stomach w as significantly elevated by exercise only in rats fed the high protei n diet. Both total and actual activities in colon were only a few perc entage of those in stomach, and those in small intestine was further l ess. These results suggest that rat stomach is the tissue active in ca tabolism of branched-chain amino acids, which is promoted by combinati on of high protein diet and exercise.