Intraluminal modulation of gastric sensitivity to distension: effects of hydrochloric acid and meal

Conscious sensations in response to gut distensions may be modulated by tem porospatial interactions among different stimuli. This study investigated w hether symptoms induced by gastric distension may be modified by hydrochlor ic acid (HCl) gastric infusion and meal ingestion. In nine healthy subjects , fixed pressure (isobaric) and fixed volume (isovolumetric) distensions we re performed during continuous (4 ml/min) intragastric saline or HCl infusi on, during fasting and after meal ingestion, until the maximal distension s tep defined as discomfort or a predefined maximal volume. During fasting is obaric distensions, the maximal distension step was significantly decreased during HCl compared with saline. The intragastric volumes were not signifi cantly different, but the wall tension was significantly lower during HCl t han saline. HCl increased gastric compliance. Meal ingestion relaxed the st omach and decreased the pressure at the maximal distension step during sali ne, but HCl did not further decrease it compared with fasting. During isovo lumetric distensions, HCl also increased gastric compliance, but in both fa sted and fed states it did not modify the maximal distension steps. In conc lusion, sensations in response to gastric isobaric distensions, but not to isovolumetric distensions, are influenced by gastric acid infusion and meal ingestion. The effects of HCl might be related to a sensitization of mucos al mechanoreceptors.