RECOGNITION OF A PHARYNGOESOPHAGEAL SPHINCTER INHIBITORY REFLEX IN DOGS AND ITS ROLE IN DEGLUTITION

The present study describes the 'pharyngo-oesophageal sphincter inhibi tory reflex' and its clinical significance. The study was performed on twelve anaesthetized dogs. A balloon-tipped catheter was placed withi n the pharyngo-oesophageal sphincter (POS) and another in the pharynx. The POS response to distension of the pharynx with a balloon filled w ith 2, 4 or 6 mi of water was recorded before and after application of local anaesthetic to the POS, and after successive section of the ana tomical constituents of the POS. Upon pharyngeal distension, POS press ure was reduced; the greater the distension, the greater the pressure reduction. The anaesthetized POS did not respond to pharyngeal distens ion. Section of the cricopharyngeus muscle did not influence the resti ng POS pressure or the POS response to pharyngeal distension. The POS pressure dropped significantly (P<0.0001) and was unresponsive to phar yngeal distension after section of both the cricopharyngeus muscle and the oesophageal circular muscle bundles. This shows that the cricopha ryngeus muscle is not involved in the upper oesophagus sphincter mecha nism.