title: Ng-nitro-L-arginine reduces nonadrenergic, noncholinergic relaxations of human gut.
abstract: The aim of this study was to determine whether nonadrenergic, noncholinergic inhibitory neurotransmission in human circular sigmoid colonic and internal anal sphincter muscle involves release of a nitric oxide-like substance. Colonic and sphincter muscle respond to electrical field stimulation by giving nonadrenergic, noncholinergic relaxations. After-contractions always occur in colonic muscle but only sometimes in sphincter muscle. Ng-Nitro-L-arginine abolished relaxations of sphincter muscle and partially reduced those of colonic muscle. After-contractions were undiminished as were relaxations of sphincter muscle to sodium nitroprusside. The effects of Ng-nitro-L-arginine were reversed by L-arginine. The results suggest that nitric oxide is possibly the neurotransmitter mediating nonadrenergic, noncholinergic relaxations of the human internal anal sphincter muscle.
authors.affiliation: Department of Pharmacology, Queen Mary and Westfield College, London, England.
authors.forename: D E
authors.initials: DE
authors.lastname: Burleigh
mesh_terms: D001003:Anal Canal / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D012809:Colon, Sigmoid / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D019335:Nitroarginine
chemical_list: D019335:Nitroarginine; D001120:Arginine