OBJECT: To assess the effect of acid infusion on the response of normal subjects to progressive intra-oesophageal balloon distension (IOBD). METHODS: Twenty-one volunteers underwent slow IOBD. Subjects were asked to indicate the first perception of sensation (S1) and the onset of pain (S2), balloon volumes being recorded at both points. A 15-min infusion of 0.1 M HCl (8 ml/min) was then instilled proximal to the balloon. Subjects were designated as acid-sensitive if they reported chest pain or heartburn during the acid infusion. Thereafter S1 and S2 were assessed again in the same manner. RESULTS: Nine subjects were acid-sensitive, 12 were acid-insensitive. The subgroup of 12 acid-insensitive subjects had an increase of pain threshold after acid infusion (P < 0.05), whereas the nine acid-sensitive subjects showed a decrease of pain threshold after acid infusion (P < 0.05). No change of the threshold for sensation occurred in either of these groups after acid infusion. CONCLUSION: Individuals showing mucosal acid sensitivity have a lower threshold for mechanoreceptor stimulation after acid exposure.
OBJECT: To assess the effect of acid infusion on the response of normal subjects to progressive intra-oesophageal balloon distension (IOBD). METHODS: Twenty-one volunteers underwent slow IOBD. Subjects were asked to indicate the first perception of sensation (S1) and the onset of pain (S2), balloon volumes being recorded at both points. A 15-min infusion of 0.1 M HCl (8 ml/min) was then instilled proximal to the balloon. Subjects were designated as acid-sensitive if they reported chest pain or heartburn during the acid infusion. Thereafter S1 and S2 were assessed again in the same manner. RESULTS: Nine subjects were acid-sensitive, 12 were acid-insensitive. The subgroup of 12 acid-insensitive subjects had an increase of pain threshold after acid infusion (P < 0.05), whereas the nine acid-sensitive subjects showed a decrease of pain threshold after acid infusion (P < 0.05). No change of the threshold for sensation occurred in either of these groups after acid infusion. CONCLUSION: Individuals showing mucosal acid sensitivity have a lower threshold for mechanoreceptor stimulation after acid exposure.