Influence of different intragastric stimuli on triggering of transient lower oesophageal sphincter relaxation in the dog

Gastro-oesophageal reflux in the dog is mainly caused by transient lower oe sophageal sphincter relaxation (TLOSR), the major stimulus for which is dis tension of the stomach. The possibility that liquid and/or acid sensors in the proximal stomach reduce the incidence and/or shorten the duration of TL OSR was addressed in the present study. Manometric recordings of the pharyn x, oesophagus, lower oesophageal sphincter and stomach were made in awake d ogs equipped with an oesophagostomy. TLOSRs were induced by insufflation of air or infusion of liquid nutrients with varying pH. Intragastric dis tens ion with air provoked TLOSRs with a significantly shorter duration than tho se seen after distension wish liquid (4.3 +/- 0.5 vs 9.6 +/- 0.3 sec; P < 0 .05). There were fewer TLOSRs at high intragastric pH (pH 5.0: 3.1 +/- 0.5/ 90 min) than at low pH (pH 1.5: 5.5 +/- 0.9/90 min, P < 0.05). Successfully propagated peristalsis following a TLOSR was more common after stimulation with liquid than with air. It can be concluded that there are H+-sensing m echanisms in the stomach which stimulate triggering of TLOSR. In addition, the reduced duration of TLOSR during air insufflation shows that the physic al state of the distending stimulus can affect the patterning of TLOSR.