GLYCOGENOLYTIC EFFECTS OF EPINEPHRINE IN SKELETAL MUSCLES OF HYPOPHYSECTOMIZED RATS TREATED WITH GLYCOPEXIC HORMONES

Abstract

IN A previous study, it was shown that in normal female rats, cortisone acetate inhibited the glycogenolytic action of epinephrine in the rectus femoris and abdominal muscles but not in the diaphragm (Wortman and Leonard, 1953). On the other hand, adrenalectomy increased the glycogenolytic effect of epinephrine in rat skeletal muscle (Collip, Thomson and Toby, 1936) but this could be prevented by treatment with adrenal cortical extracts (Winternitz and Long, 1952). Epinephrine administered intravenously to fed normal and hypophysectomized rats reduced muscle glycogen equally in both instances, but if given subcutaneously, epinephrine was less effective in hypophysectomized rats (Russell and Cori, 1937). It appears that the antagonistic action between glycogenolytic and glycopexic hormones in different skeletal muscles requires further study, particularly since it is usually inferred that skeletal muscles react similarly.

Since muscle glycogen of fasting hypophysectomized rats can be increased or maintained at normal levels by a number of glycopexic hormones (Russell and Wilhelmi, 1950; Leonard, 1953)