Adenyl cyclase in normal and denervated skeletal muscles.

Adenyl cyclase (AC) has been studied in homogenates and crude plasma membranes from normal and denervated red and white skeletal muscle from male rats. Basal-, NaF- and epinephrine-stimulated activities were increased in homogenates of both types of muscles after nerve transection, supporting a possible role of the cAMP-AC system in the neurotrophic control of skeletal muscle. AC-specific activity was increased 10 times in crude plasmic membranes from normal muscle if compared to that of homogenate. It was decreased in crude plasmic membrane from denervated muscle. The correlation of our results with other results on cAMP concentrations and cAMP phosphodiesterase (PDE) activities in denervated muscle suggests that factors other than AC and PDE might control the synthesis and degradation of cAMP.