Molecular Pharmacology, Vol 13, 976-979, Copyright © 1977 by the American Society for Pharmacology and Experimental Therapeutics

The Action of Halothane on Adenylate Cyclase

¹ Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York 10032

Halothane, at concentrations of from 1-10 volume %, significantly increased adenylate cyclase activity in rat uterine homogenates. The activation of adenylate cyclase by halothane was not altered by propranolol. The inhibitory effect of this beta adrenergic blocking compound on isoproterenol-stimulated adenylate cyclase was not changed by halothane, while the stimulation of adenylate cyclase by isoproterenol, including the maximally effective concentration, was enhanced. The activation of the enzyme by other agonists—prostaglandin E₁, sodium fluoride, and 5'-guanylylimidodiphosphate—was also markedly increased by halothane at each concentration of the agonists tested, including maximally effective concentrations. It is proposed that halothane exerts its action on uterine adenylate cyclase through conformational changes of the catalytic unit, resulting in a higher activity of the enzyme.

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ACKNOWLEDGMENTS The authors thank Mrs. Olga Zak and Miss Gunilla Thulin for their excellent technical assistance.