Loss of the adrenoceptor-mediated secretory drive on the rat parotid gland during eating and the effect on parasympathetic substance P and VIP.

Phentolamine and propranolol (2 mg/kg i.p. of each) were administered to rats to be fed hard chow over a period of 80 min and to their fasting controls. The pharmacological elimination of the adrenoceptor mediated secretory drive on the parotid gland cells during feeding did not affect the gland content of the peptides substance P and vasoactive intestinal peptide localized to parasympathetic nerve fibres of the gland and thought to transmit secretory impulses. This is in contrast to the previously demonstrated effect of elimination of the parasympathetic acetylcholine-evoked secretion following administration of atropine, which resulted in reduced gland contents of these peptides.