Effects of nutrients and serotonin 5-HT3 antagonism on symptoms evoked by distal gastric distension in humans

Distal gastric distension may contribute to meal-related dyspeptic symptoms . This study's aims were to determine the effects of distinct nutrient clas ses on symptoms induced by distal gastric distension and their dependence o n 5-hydroxytryptamine(3) (5-HT3) receptors. Nine healthy subjects rated pai n, nausea, and bloating induced by isobaric distal gastric distensions (6-2 4 mmHg) during duodenal lipid, carbohydrate, protein, or saline perfusion a fter treatment with placebo or the 5-HT3 receptor antagonist granisetron (1 0 mug/kg iv). Distensions produced greater pain, nausea, and bloating with lipid at 1.5 kcal/min compared with saline (P less than or equal to 0.02), primarily because of greater distal gastric volumes at each distending pres sure. In contrast, carbohydrate and protein had no significant effect. At 3 kcal/min, lipid increased symptoms through a volume-independent as well as a volume-dependent effect. Granisetron did not affect symptom perception o r gastric pressure-volume relationships. In conclusion, isobaric distal gas tric distension produces more intense symptoms during duodenal lipid compar ed with saline perfusion. Symptom perception during distal gastric distensi on is unaffected by 5-HT3 receptor antagonism.