- AMER PHYSIOLOGICAL SOC
The pharynx is very important for elicitation of reflex swallowing. The region of the pharynx is innervated by the pharyngeal branch of the glossopharyngeal nerve (GPN-ph). Nitric oxide ( NO) plays an important role in various physiological functions. The purpose of this study is to investigate the contribution of NO to reflex swallowing evoked by electrical stimulation of the GPN-ph. Swallowing was evoked in urethane-anesthetized rats by application of repetitive electrical stimulation ( 10- to 20-mu A amplitude, 10- to 20-Hz frequency, 1.0-ms duration) to the central cut end of the GPN-ph or superior laryngeal nerve. Swallowing was identified by electromyographic activity of the mylohyoid muscle. Latency to the first swallow and the interval between swallows were measured. Intravenous administration of N-G-nitro-L-arginine ( L- NNA, 0.6 mg/ kg), a nonselective inhibitor of NO synthase ( NOS), extremely prolonged latency to the first swallow and the interval between swallows evoked by the GPN-ph. Intraperitoneal administration of 7-nitroindazole (5.0 mg/ kg), a selective inhibitor of neuronal NOS, significantly prolonged latency to the first swallow and the interval between swallows evoked by the GPN-ph. Administration of L- arginine ( an NO donor, 500 mg/ kg) and sodium nitroprusside ( an NO releaser, 0.6 mg/ kg) restored the suppression of swallowing induced by the NOS inhibitor. Superior laryngeal nerve-evoked swallowing was suppressed by administration of a higher dose of L- NNA (6.0 mg/ kg). Swallowing evoked by water stimulation of the pharynx was also suppressed by L- NNA ( 0.6 mg/ kg). These results suggest that NO plays an important role in signal processing for initiation of reflex swallowing from the pharynx.
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- DOI : 10.1152/ajpregu.00646.2005
- ISSN : 0363-6119
- Web of Science ID : WOS:000239658800022