Effect of Epinephrine on Phosphorylase and Glycogen Levels in the Rat Uterus

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Abstract
An intraperitoneal injection of eipinephrine into spayed rats, treated with estradiol benzoate 48 hr before, decreased uterine phosphorylase α (active) activity and glycogen concentration slightly within 5 min and to a minimum within 30–60 min. The restoration of enzyme activity occurred abruptly between the 2nd and 3rd hr, but the recovery of glycogen was gradual and was attained approximately at the 8th hour. Spayed rats were treated with estradiol and epinephrine concurrently, and with additional epinephrine at intervals for 6 hr. Others received only estradiol or no treatment. Epinephrine inhibited the effects of estradiol to increase uterine weight, phosphorylase a activity and glycogen deposition. Epinephrine also produced uterine vasoconstriction. Interruption of the uterine blood supply in estrogenprimed rats for 10 min caused a decrease in phosphorylase a activity and in glycogen concentration similar to that observed 15 min after treatment with epinephrine. From these observations and others, it is proposed that uterine vasoconstriction resulting from injections of epinephrine is a contributing factor in causing the simultaneous decrease in enzyme activity and glycogen observed in these experiments.