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 classes on symptoms induced by distal gastric distension and their dependence on 5-hydroxytryptamine(3) (5-HT3) receptors. Nine healthy subjects rated pain, nausea, and bloating induced by isobaric distal gastric distensions (6-24 mmHg) during duodenal lipid, carbohydrate, protein, or saline perfusion after treatment with placebo or the 5-HT3 receptor antagonist granisetron (10 microg/kg iv). Distensions produced greater pain, nausea, and bloating with lipid at 1.5 kcal/min compared with saline (P < or = 0.02), primarily because of greater distal gastric volumes at each distending pressure. 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 or gastric pressure-volume relationships. In conclusion, isobaric distal gastric distension produces more intense symptoms during duodenal lipid compared with saline perfusion. Symptom perception during distal gastric distension is unaffected by 5-HT3 receptor antagonism.