Inhibition of Hormone-Sensitive Adenyl Cyclase by Phenothiazines

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Abstract
Chlorpromazine (3 x 10(-4)M) prevents the stimulation of adenyl cyclase activity in thyroid membranes produced by thyrotropin and prostaglandin, ACTH stimulation of adenyl cyclase in adrenal tissue, and glucagon- and epinephrine-stimulation of adenyl cyclase activity in liver. Baseline activity is unaffected. Parathyroid hormone stimulation of kidney preparations was not inhibited under these conditions. At chlorpromazine concentrations >3 x 10(-4)M F(-)-stimulated cyclase activity of thyroid and adrenal tissue was increased. Other phenothiazines, trifluoperazine, and prochlorperazine, have similar effects on thyrotropin and F(-)-stimulated cyclase activity of thyroid. Na(+)- K(+)-dependent ATPase of thyroid is also inhibited by chlorpromazine. Since thymol causes a similar dissociation of hormone- and F(-)-stimulated adenyl cyclase, it is concluded that the surface properties of these agents best account for their effects on adenyl cyclase.