Role of nitric oxide in esophageal peristalsis.
In vitro studies have suggested that NO may be a nonadrenergic, noncholinergic inhibitory mediator in the esophageal body. We examined the role of NO in physiological peristalsis in anesthetized opossums by assessing the effect of the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) on esophageal contractions induced by swallows, prolonged vagal efferent nerve stimulation, and midesophageal balloon distension. A perfused manometry system measured intraluminal pressures 1 and 5 cm orad to the lower esophagus, and suction electrodes monitored membrane potential changes at the same locations. NO synthase inhibition 1) decreased swallow-induced contraction amplitude in the distal esophagus and, when combined with atropine, abolished these contractions; 2) diminished swallow-induced contraction latencies, predominantly in the distal esophagus, thereby decreasing the latency gradient and increasing the peristaltic velocity; 3) abolished vagal-stimulation-induced, end-of-stimulus "B" contractions and either unmasked or increased the amplitude of intrastimulus "A" contractions; 4) abolished the contractions occurring at the end of balloon distension; and 5) inhibited the membrane hyperpolarization and the subsequent nonadrenergic, noncholinergic depolarization induced by all three stimuli. These data support the hypothesis that NO is a mediator of nonadrenergic, noncholinergic neurotransmission in the opossum esophagus. Furthermore, the data suggest that esophageal peristalsis is mediated by a "blended" activation of cholinergic and nonadrenergic, noncholinergic (via NO) neurons.
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Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada.
Paterson
W G
WG
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D002404:Catheterization; D003679:Deglutition / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D004947:Esophagus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D009893:Opossums; D010528:Peristalsis / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology
D009569:Nitric Oxide; D001285:Atropine; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester