[Inhibition of postoperative muscular proteolysis by sodium alpha-ketoisocaproate: does a dose-effect relation exist?].

The inhibitory effect of branched chain amino acids on muscle protein breakdown has been attributed to the ketoanalogue of leucine, alpha-ketoisocaproic acid. In an attempt to demonstrate a possible dose-response relationship for ketoleucine, the postoperative protein breakdown (using urinary excretion of 3-methylhistidine, creatinine and nitrogen) was evaluated in 29 patients undergoing gynaecological surgery. They were randomly assigned to one of the following groups: group A (ten patients) received 3 g of glucose per kilo and per day, group B (ten patients) received glucose + 100 mg X kg-1 X d-1 of ketoleucine and group C (nine patients) glucose + 200 mg X kg-1 X d-1 of ketoleucine. The study was performed over a period of 72 h. The 3-methylhistidine/creatinine ratio was significantly lower in groups B and C than in group A (respectively 28.47, 28.07 and 32.08). These results confirmed the inhibitory effect of ketoleucine on muscle protein breakdown. However there was no difference between group B and group C. In conclusion, this study did not demonstrate a dose-response relationship for ketoleucine in moderate postoperative catabolism.