THE LOCAL AND SYSTEMIC EFFECTS OF MINOR INJURY ON MUSCLE PROTEIN-SYNTHESIS IN THE RAT

Massive physical trauma has marked effects on metabolism of body tissu es. At present, however, there is little data available on the effect of minor injury on protein metabolism. In this study we examined the e ffects of a minor muscle injury on the rate of protein synthesis in in jured muscle as well as its contralateral control. Rats were injured b y removing a small piece of tissue from the interior of one gastrocnem ius muscle. Muscle protein synthesis was measured in vivo by a floodin g dose technique. The injury had no significant effect on food intake, body weight, muscle protein content or plasma insulin concentration a t any time during the following 48 hr. However the rate of protein syn thesis in the injured muscle increased 48 hr after injury (mean value in injured muscle 16.1 +/- 1.8 (SEM, n=18) % per day, uninjured muscle in the same animals 13.1 +/- 1.3% per day, P < 0.05 by paired t-test) . These results indicate that even a minor injury causes a local incre ase in the rate of protein synthesis 48 hr later. This may be an oblig atory part of the process of repair and regrowth of muscle tissue.