Acute hypertrophic response of skeletal muscle to removal of synergists.

The purpose of this project was to study the initial rapid enlargement phase of skeletal muscle in response to ablation of synergistic muscles. The first experiment tested the hypothesis that this initial phase is due to inflammation in the enlarging muscle. The wet weight of the plantaris muscle increased significantly (14%) within 1 h after removal of the ipsilateral gastrocnemius muscle. This increase was due to inflammation, as evidenced initially by edema, and within the next few hours, by leukocyte invasion of the interstitium and enhanced hexose monophosphate shunt-reducing capacity. In the second experiment we followed the time course of this inflammatory reaction. The response peaked at 1-5 days following surgery, after which it subsided to control levels by 16 days postsurgery. The final experiments were designed to uncover the factor(s) causing the inflammatory response. Two possible mechanisms were hypothesized: 1) trauma resulting from surgical manipulation of the tissue, and 2) trauma due to elevated stretch and/or tension on the muscle following removal of the synergists. The data indicate that surgical trauma is the causative factor of the inflammatory response in this hypertrophy model.