Substance K and salivary secretion in the rat.

Intravenous injections of substance K (SK), a novel member of the family of tachykinins, evoked secretion from the three major salivary glands of the rat in the presence of muscarinic, alpha-adrenergic and beta-adrenergic receptor blockade; the submaxillary glands contributed most and the sublingual glands least to the total volume secreted. SK was less potent than substance P (SP) in evoking fluid and amylase secretion. However, the amylase concentration in parotid saliva evoked by SK was twice that evoked by SP, a finding which indicates that in the glands there are more than just one type of tachykinin receptors. Vasoactive intestinal peptide enhanced the SK evoked fluid response and increased the amylase concentration in parotid saliva. SK is a possible transmitter involved in the atropine-resistant parasympathetic nerve evoked salivation in the rat.