Abstract
Summary
Following denervation of the rat rectus femoris muscle, phosphorylase a and t activity and the a/t ratio were maintained for 5 days, decreased by 10 days and remained low for 60 days. In muscles denervated for 15 days epinephrine increased the activity of phosphorylase a and t and the a/t ratio, and markedly inhibited the expected decrease in enzyme activity which follows tetanic contraction. Following electrical stimulation, the recovery of 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 the denervated muscle. Changes in muscle phosphorylase activity after denervation atrophy differ from those incurred from other causes.
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