Mechanoreceptors of the proximal stomach and perception of gastric distension

OBJECTIVES: To assess the role of tension receptors in gastric perception by pharmacologically modifying gastric contractile activity during isovolumetric distensions of the proximal stomach with the hypothesis that relaxation decreased perception and contraction increased it. METHODS: Fourteen healthy subjects underwent two 30-min isovolumetric (75% of the threshold volume for discomfort) distensions using a barostat. During the second distension, either gastric relaxation was induced by intravenous (i.v.) glucagon 4.8 microg/kg bolus plus 9.6 microg/kg per h or contraction by i.v. erythromycin 3 mg/kg. Hunger and fullness were assessed with a 100-mm analog scale before and at 15 and 30 min during each distension. RESULTS: Glucagon decreased baseline intrabag pressure (8.4 +/- 1.0 vs 10.7 +/- 1.3 mmHg; p < 0.05) and abolished the pressure waves (0 vs 16.7 +/- 2.3) when compared with placebo, whereas erythromycin increased baseline pressure (13.2 +/- 1.0 vs 11.9 +/- 0.9 mmHg; p < 0.05) and the rate of pressure waves (31.7 +/- 5.4 vs 20.5 +/- 3.1; p < 0.05). Fullness increased (p < 0.05) during distension, but it was unaffected by either of the drugs: Delta score (i.e., score during distension--baseline score) of 38 +/- 10 mm (glucagon) versus 22 +/- 10 (placebo) and 24 +/- 17 mm (erythromycin) versus 36 +/- 14 (placebo) at 15 min. Similar observation were made at 30 min. Hunger was influenced neither by distension nor by any of the two drugs consistently. CONCLUSIONS: Our data do not support a prominent role of tension receptors of the proximal stomach on perception of fullness, suggesting that stretch, that is, volume, is the more relevant stimulus.