Phosphorylase kinase isozymes and phosphorylase in denervated skeletal muscles

The effects of motor denervation on levels of phosphorylase kinase isozymes and phosphorylase were investigated in rat epitrochlearis, hemidiaphragm, and soleus muscles. Amounts of the proteins were measured after quantitative immunoprecipitation and found to be decreased by as much as 70% 2 weeks after denervation. Unexpectedly, denervation had little, if any, effect on the relative proportions of the two phosphorylase kinase isozymes. Phosphorylase and phosphorylase kinase were decreased by essentially the same extent after denervation, and the effects of denervation were comparable in all three muscles. The decreases in these enzymes explain, at least in part, the marked alterations in glycogen metabolism that occur after motor denervation.