Independence of β-adrenergic and thyrotropin receptors linked to adenylate cyclase in the thyroid

Abstract

CATECHOLAMINES stimulate thyroid function in several species, including cattle, man and mouse (brief review in ref. 1). As with the pituitary-derived tropic hormone, thyrotropin, an initial step in this process seems to be stimulation of adenylate cyclase associated with the thyroid cell plasma membrane, leading to increased intracellularad adenosine-3′-5′ cyclic monophosphate (cyclic AMP). The response to catecholamines is mediated by a β-adrenergic receptor^2,3 and we have examined whether, for a given membrane preparation, the response of adenylate cyclase to the β -adrenergic agonist isoproterenol can be varied independently of the response to thyrotropin. Our results indicate that the two receptor–adenylate cyclase systems function separately.