Dissociation of cyclic 3′,5′-guanosine monophosphate. Accumulation and secretory inhibition in the action of carbamylcholine on thyroid

Abstract

A calcium cyclic GMP regulatory system has been demonstrated in thyroid [1 ]. Acetylcholine through calcium activates cyclic GMP accumulation [ 1,2]. It also depresses the TSH induced cyclic AMP accumulation and thyroid secretion [1]. NaF, KC1 and Ca 2+ in the presence of ionophore A23187 have similar effects [1,2]. As in other systems [3,4] the role of cyclic GMP in the regulation of thyroid metabolism remains unclear. Specifically, cyclic GMP accumulation could be the necessary link in acetylcholine action or a side effect of the rise in cytosol Ca 2+. The purpose of the present communication is to show that cyclic GMP accumulation can be dissociated from the inhibition of secretion by acetylcholine which suggests that this nucleotide is not the mediator of this effect.