BRANCHED-CHAIN TRANSAMINASE AND KETO ACID DEHYDROGENASE-ACTIVITIES INBURNED RATS - EVIDENCE FOR A DIFFERENTIAL ADAPTATION ACCORDING TO SEX

Female and male rats show differences in nitrogen metabolism after tra uma, and the contribution of the branched-chain amino acid oxidizing p athway following thermal injury was evaluated. Female and male rats we re subdivided into baseline, burned and unburned, pair-fed groups. Bur ned and pair-fed rats were sacrificed on days 1, 2, and 3 postburn, an d branched-chain amino acid transaminase (BCTA), branched-chain alpha- keto acid dehydrogenase (BCKDH) activated and total, and succinate deh ydrogenase (SDH) activities were measured in red and white muscle and in liver; BCTA was not measured in liver. Baseline and pair-fed groups had similar enzyme activities. Changes following thermal injury were: (I) elevated SDH iu all tissues for both sexes; (2) increased BCTA ac tivity in red and white muscles from male rats; and (3) increased perc entage of activated BCKDH in red and white muscles on days 2 and 3 for male rats. All other activities were unchanged. These findings agree with previous post trauma differences in urinary nitrogen losses in fe male and male rats. The results show that the enzymes for oxidation of the branched-chain amino acids in males respond to injury while those do not in females. (C) Elsevier Science Inc. 1997.