Complementary action of substance P and vasoactive intestinal peptide on the rat parotid secretion.
Augmentation of the rat parotid salivary secretion to intravenous injections of substance P (SP) occurred when SP was combined with vasoactive intestinal peptide (VIP), or stimulation of the auriculo-temporal nerve in the presence of atropine and the adrenergic blockers, dihydroergotamine and propranolol. The largest increase was obtained when SP (0.5 micrograms kg-1) was used together with subthreshold doses of VIP (84% at 0.05 micrograms kg-1 and 105% at 0.5 micrograms kg-1) and low frequency stimulation (92% at 2 Hz and 97% at 5 Hz), which did not produce any salivary secretion by itself. There was no facilitated secretion when VIP and nerve stimulation were combined. Amylase output was much larger (250-500%) when SP was combined with nerve stimulation (0.5-5 Hz) or VIP (0.005-5 micrograms kg-1) than when SP was used alone. Similar results were obtained in rats where the auriculo-temporal nerve was stimulated during the early phase (24-90 h) of Wallerian degeneration, when the nerve-induced responses were seemingly completely blocked. Our results are consistent with the hypothesis that both VIP and SP contribute to the atropine-resistant parotid secretion, and that they have a complementary role in the rat parotid exocrine function.
J
J
Ekström
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L
Olgart
D000681:Amylases / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D009410:Nerve Degeneration / Q000187:drug effects; D010275:Parasympathetic Nervous System / Q000187:drug effects; D010306:Parotid Gland / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012463:Saliva / Q000378:metabolism*; D013373:Substance P / Q000494:pharmacology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D001285:Atropine; D000681:Amylases