Abstract
The purpose of this study is to investigate whether NO modulates initiation of reflex swallowing. Recent studies have revealed that nitric oxide synthase (NOS) is located in brain stem regions involved with swallowing. However, little is known regarding the contribution of NO to reflex swallowing. Urethan-anesthetized rats were used. To evoke swallowing, the pharyngeal branch of the glossopharyngeal nerve (GPN-ph) and the superior laryngeal nerve (SLN) were stimulated by repetitive electrical stimulation (10-80μA,10-30Hz,1.0ms). The latency for the first swallow and the time interval between swallows were measured. N-nitro-L-arginine (L-NNA), an inhibitor of NOS, L-arginine (L-Arg) and sodium nitroprusside (SNP), NO donors, were intravenously administrated. L-NNA extremely reduced occurrence of swallows evoked by the GPN-ph, whereas swallows evoked by the SLN were only slightly changed. On the other hand, L-Arg and SNP facilitated reflex swallowing. These results indicate that NO modulates reflex swallowing and plays an important role in the initiation of reflex swallowing especially evoked by the GPN-ph. [Jpn J Physiol 54 Suppl:S178 (2004)]
