Comparison of cholinergic inhibition and beta-adrenergic stimulation of adenylate cyclase from rat and guinea-pig hearts: effects of guanine nucleotides and monovalent cations.

Adenylate cyclase activities and the effects of isoproterenol (a beta-adrenergic receptor agonist), carbachol (a cholinergic receptor agonist) and forskolin (a plant diterpene) were determined in homogenates and washed particulate fractions prepared from rat and guinea-pig hearts. Many interesting differences were noted in the stimulatory and inhibitory effects of isoproterenol and carbachol respectively on the heart enzyme. The likely significance of these results is presented.