Nitric oxide induces acetylcholine-mediated contractions in the guinea-pig small intestine.
In longitudinal muscle/myenteric plexus preparations of the guinea-pig ileum, exogenous nitric oxide (NO) induced concentration-dependent relaxations. In tissues at basal tone, NO (3 x 10(-6) M) induced a moderate relaxation followed by a pronounced contraction, consisting of a quick and sustained component. Tetrodotoxin (5 x 10(-7) M) abolished both phases of the contraction. Atropine (5 x 10(-7) M) abolished the quick component and reduced the sustained component of the contraction; the latter was further suppressed by the selective NK1 receptor antagonist CP 96,345. Hexamethonium (5 x 10(-5) M) failed to affect the contractile response to NO. It is concluded that administration of exogenous NO in the guinea-pig ileum can lead to activation cholinergic and to a lesser degree tachykininergic neurones.
Barthó
L
L
Department of Pharmacology, University Medical School, Pécs, Hungary.
Lefebvre
R
R
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D018738:Hexamethonium / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D013373:Substance P / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D001713:Biphenyl Compounds; D009569:Nitric Oxide; D013373:Substance P; D018738:Hexamethonium; D013779:Tetrodotoxin; D001285:Atropine; D000109:Acetylcholine; C066892:CP 96345