Phosphorylase Activity in Denervated Skeletal Muscle.

Abstract

Following denervation of the rat rectus femoris muscle, active phosphorylase a and total phosphorylase t and a/t ratios were maintained for 5 days, decreased by 10 days and remained low for 60 days. In muscles denervated for 15 days, epinephrine increased phosphorylase a and t activity and the a/t ratios, and markedly inhibited the expected decrease in enzyme activity which follows tetanic contraction. Following electrical stimulation, the recovery of the activity ratios in both intact and denervated muscles occurred at the same time. In denervated muscle, the return of phosphorylase a and t was delayed, as compared to that in normal muscle. Epinephrine showed no effect on the recovery of enzyme activity in denervated muscle. Changes in muscle phosphorylase activity after denervation atrophy differ from those incurred from other causes.