title: Modulation of cholinergic neurotransmission by vasoactive intestinal peptide in ferret trachea.
abstract: We studied the effect of vasoactive intestinal peptide (VIP) on the contractile responses to electrical field stimulation (EFS) in isolated ferret tracheal segments. VIP did not change resting tension up to 2 X 10(-7) M, but it showed a biphasic effect on the responses to EFS. In concentrations up to 10(-9) M, VIP potentiated the response; at higher concentrations VIP reduced responses. Thus, at a concentration of 10(-9) M, VIP decreased the mean (+/- SE) log EFS frequency, producing 50% of maximum contraction significantly from a control value of 0.476 +/- 0.062 to 0.214 +/- 0.057 Hz (P less than 0.01); at a concentration of 2 X 10(-7) M VIP increased the half-maximal frequency from a control value of 0.513 +/- 0.086 to 0.752 +/- 0.053 Hz (P less than 0.05). The potentiating effect of VIP (10(-9) M) was not inhibited by hexamethonium, indomethacin, pyrilamine, methysergide, or [D-Pro2,D-Trp7,9] substance P. The inhibitory effect of VIP (2 X 10(-7) M) was also not inhibited by hexamethonium, indomethacin, or naloxone. In contrast to EFS-induced contraction, contractions produced by acetylcholine (10(-9) to 10(-3) M) were not affected by VIP at concentrations of 10(-9) and 2 X 10(-7) M. These results suggest that VIP modulates contractions produced by EFS via presynaptic cholinergic mechanisms and probably through a specific VIP receptor.
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco 94143.
authors.forename: K
authors.initials: K
authors.lastname: Sekizawa
authors.forename: J
authors.initials: J
authors.lastname: Tamaoki
authors.forename: P D
authors.initials: PD
authors.lastname: Graf
authors.forename: J A
authors.initials: JA
authors.lastname: Nadel
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D005289:Ferrets; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
chemical_list: D014660:Vasoactive Intestinal Peptide; D000109:Acetylcholine; D007213:Indomethacin