Nitric oxide as a putative nonadrenergic noncholinergic inhibitory transmitter in the canine pylorus in vivo.
Antropyloroduodenal motility was recorded in seven anesthetized dogs to assess the role of nitric oxide and L-arginine metabolites in nonadrenergic noncholinergic (NANC) mediation of pyloric relaxation. Pyloric activity induced by duodenal field stimulation was inhibited by antral field stimulation and electrical vagal stimulation. Intra-arterial NG-L-arginine-methyl-ester (L-NAME) reduced the inhibition from antral or vagal stimulation (P less than 0.05). Intravenous infusion of L-NAME also blocked the inhibitory effect of vagal and antral stimulation but left the tetrodotoxin-insensitive action of intra-arterial vasoactive intestinal peptide (VIP) and sodium nitroprusside unchanged. L-Arginine reversed the effect of L-NAME whereas D-arginine did not. L-NAME enhanced pyloric contractions to intra-arterial acetylcholine. The NANC inhibition of the substance P-stimulated pyloric response in vitro was blocked by L-NAME and reversed by addition of L-arginine. Sodium nitroprusside was effective as a relaxant in vitro but VIP was not. These data suggest that metabolites of L-arginine mediate neural inhibition of canine pyloric motor activity.
Department of Biomedical Sciences, McMaster University, West Hamilton, Ontario, Canada.
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Allescher
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D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009130:Muscle, Smooth / Q000294:innervation; D019331:NG-Nitroarginine Methyl Ester; D009433:Neural Inhibition; D018377:Neurotransmitter Agents / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D011708:Pylorus / Q000187:drug effects / Q000502:physiology*; D013237:Stereoisomerism; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D018377:Neurotransmitter Agents; D009599:Nitroprusside; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester