title: Differentiation between myenteric plexus and longitudinal muscle of the rat jejunum as the site of action of putative enteric neurotransmitters.
abstract: The contribution of the myenteric plexus in the mechanical responses of rat jejunal longitudinal muscle produced by several enteric nerve substances was evaluated. The myenteric plexus of a segment of rat jejunum was destroyed by serosal application of benzalkonium chloride (BAC). Fifteen days after BAC treatment, both the BAC-treated and an orad control jejunal segment were removed and the mechanical responses of the longitudinal muscle produced by the following substances were examined: substance P, acetylcholine (ACh), 5-hydroxytryptamine (5-HT), cholecystokinin octapeptide (CCK-8), norepinephrine, vasoactive intestinal peptide (VIP), bombesin, [Leu5]enkephalin and somatostatin. Our results indicate that: substance P and norepinephrine produce their mechanical responses by acting predominantly on the longitudinal smooth muscle; 5-HT, CCK-8, ATP, VIP and neurotensin act predominantly through the myenteric plexus; ACh possesses both direct and indirect actions; and because the responses to [Leu5]enkephalin, bombesin and somatostatin were equivocal, a conclusion as to their site of action could not be made with this preparation.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D007583:Jejunum / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009197:Myenteric Plexus / Q000502:physiology*; D009496:Neurotensin / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D018377:Neurotransmitter Agents; D012701:Serotonin; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D009496:Neurotensin; D000255:Adenosine Triphosphate; D012844:Sincalide; D000109:Acetylcholine; D001839:Bombesin; D009638:Norepinephrine