Palmaris longus (PML) muscles of rhesus monkeys were transplanted, with or without anastomosis of the median nerve, to the nerve stump of the autograft. Because PML autografts revascularize spontaneously, vascular anastomoses were not performed. Muscle fibers regenerated in all autografts with neuroanastomosis, but in only three of eight autografts without neuroanastomosis. Five autografts without neuroanastomosis were replaced by noncontractile connective tissue. Growth and differentiation of muscle fibers into three fiber types and development of capillarity were analyzed histochemically, and succinate oxidase activity of whole-muscle homogenates was determined. None of these measures reached values for control PML muscles within 100 days of transplantation. In comparison to control muscles, autografts had slower times to peak tension and less absolute tension, but similar tension per square centimeter of muscle fiber cross-sectional area. Monkey PML autografts with neuroanastomosis were similar in structure and function to cat extensor digitorum longus autografts that had not had neuroanastomosis.

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Protein synthesis in skeletal muscle following acute exhaustive exercise.

Cell-free and whole-tissue protein synthesis was studied in skeletal muscle of untrained male guinea pigs that had undergone a treadmill run to exhaustion. Experiments using explants from the gastrocnemius muscle maintained in organ culture demonstrated that the ability of the acutely exercised muscle to incorporate amino acids into protein had increased. Compared to polyribosomes prepared from several lower hind limb muscles of nonexercised guinea pigs, polyribosomes from the same muscle in exhausted guinea pigs had incorporated almost 50% more radioactive leucine into protein. However, the polysome profiles of control and exercised muscle were identical, and no difference in the total polysome RNA content could be detected. The efficiency of in-vitro protein synthesis using washed membrane-bound polyribosomes (microsomes) isolated from acutely exercised skeletal muscle was 50% greater than with microsomes from rested control muscle.

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