Effects of cholinergic and adrenergic agonists on the secretion of fluid and protein by submandibular glands of the hamster and the rat.

1. Significant differences were observed between the hamster and the rat in terms of the secretion of fluid and protein from submandibular glands in response to pilocarpine, phenylephrine and isoproterenol. 2. In both the rat and the hamster the secretory responses induced by pilocarpine, phenylephrine and isoproterenol were inhibited by pretreatment with 4-DAMP, prazosin and metoprolol, respectively. 3. These results suggest that the submandibular glands of the hamster and the rat have M3-cholinoreceptors, as well as alpha 1- and beta 1-adrenoceptors, and that these receptors play different roles in the secretion of fluid and protein from hamster and rat submandibular glands.