Effect of Prostaglandin E1 Administration on the Liver Glycogen Synthetase and Phosphorylase Systems
Randall T. Curnow 1 and Frank Q. Nuttall 1
From the
1 From the Medical Service and Endocrine-Metabolic Section, Veterans Administration Hospital, and the Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55417
The effects of intravenous administration of prostaglandin E1 (PGE1) on the glycogen synthetase and phosphorylase systems in rat liver have been studied. It was found that PGE1 caused a significant decrease in synthetase I activity that was not influenced by alterations in nutritional status or presence or absence of adrenal glands. Furthermore, ß adrenergic and ganglionic blockade did not diminish the response of the synthetase system to PGE1.
PGE1 promoted a significant increase in liver phosphophosphorylase activity in fasted intact rats which could be completely inhibited by ganglionic blockade and partially inhibited by ß adrenergic blockade. Following PGE1 there occurred a significant decrease in liver phosphophosphorylase activity in fasted adrenalectomized rats.
It was concluded that the in vivo effects of PGE1 on the synthetase and phosphorylase systems are mediated through different mechanisms. Preliminary evidence suggests that the effect on the synthetase system may be mediated, at least in part, by a direct inhibitory action on synthetase D phosphatase. The effect of PGE1 on the phosphorylase system is considered to be mediated secondarily through a reflex release of adrenal catecholamines.
Submitted on August 18, 1971
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