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Background-In animals, activation of 5-HT 1 like receptors causes a relaxation of the gastric fundus through the activation of intrinsic inhibitory neurones. Aims-To investigate the eVect of sumatriptan, an agonist at enteric neuronal 5-HT 1 receptors, on fasting fundus tone and sensitivity to gastric distension in man. Methods-A gastric barostat was used to study the eVect of placebo and sumatriptan, 6 mg subcutaneously, on basal fundic tone in healthy subjects. In addition, stepwise isobaric and isovolumetric gastric distensions were performed and perception was measured before and after the administration of placebo and sumatriptan. Results-Placebo had no significant effects on gastric tone and on perception. Sumatriptan induced an immediate relaxation of the gastric fundus, reflected by an intragastric volume increase of 209 (39) ml (p<0.0005). After sumatriptan, intragastric pressures at the thresholds for perception or discomfort were not significantly altered. However, the intragastric volumes and the corresponding calculated wall tensions at perception and discomfort thresholds were significantly increased. Conclusions-Administration of the 5-HT 1 receptor agonist sumatriptan induces a relaxation of the gastric fundus in man, allowing larger intragastric volumes before thresholds for perception or discomfort are reached. The eVects of sumatriptan on the gastric fundus may have therapeutic potential in the treatment of patients with functional dyspepsia. (Gut 2000;46:468-473)

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Background-During the interdigestive state in humans, erythromycin 40 mg induces a premature activity front that starts in the stomach, while erythromycin 200 mg induces a prolonged period of enhanced antral contractile activity. Aims-To study the involvement of a cholinergic pathway in the motor eVects of erythromycin using the muscarinic antagonist atropine and the neural 5-HT 1 receptor agonist sumatriptan. Methods-In 30 healthy volunteers, fasted antroduodenojejunal motor activity was studied by stationary manometry. Placebo (n=10), atropine (15 µg/kg intravenous bolus plus 15 µg/kg/h over 30 minutes; n=10), or sumatriptan (6 mg subcutaneously; n=10) was administered, followed by infusion of erythromycin 40 mg or 200 mg. Results-After placebo, erythromycin 40 mg induced a premature activity front with gastric onset after 19.1 (1.7) minutes in all volunteers. After atropine, erythromycin 40 mg failed to induce a premature activity front during a 60 minute period in all volunteers (p<0.001), while sumatriptan prevented the induction of a premature activity front during a 60 minute period in all but one volunteer (p<0.005). The number of antral contractions and their mean amplitude in the 60 minutes after erythromycin 200 mg did not diVer significantly after atropine or sumatriptan versus placebo. Conclusions-The antral motor eVects of erythromycin in humans are mediated via diVerent pathways. The induction of a premature activity front is mediated through activation of an intrinsic cholinergic pathway, while the induction of enhanced antral contractile activity may be mediated via a pathway potentially involving activation of a muscular receptor. (Gut 1998;43:395-400)

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Background: Delayed gastric emptying, impaired gastric accommodation to a meal and hypersensitivity to gastric distension have been implied in the pathophysiology of functional dyspepsia. Dyspeptic patients are often treated with the prokinetic drug cisapride. Aim: To assess the effects of cisapride on perception of gastric distension and gastric accommodation to a meal. Methods: Eighteen healthy volunteers underwent a gastric barostat study on two occasions, after pre‐treatment with placebo or cisapride 10 mg q.d.s. Graded isobaric and isovolumetric distensions were performed until the subjects reported discomfort. Volume and pressure changes were recorded and perception was scored by a questionnaire. In 10 volunteers, the amplitude of the gastric accommodation to a mixed liquid meal was also measured. Results: Pre‐treatment with cisapride significantly lowered thresholds for perception and for discomfort, both during isobaric (4.3 ± 0.7 vs. 3.2 ± 0.7 and 12.2 ± 1.2 vs. 9.2 ± 0.9 mmHg above minimal distending pressure (MDP), respectively, P < 0.05) and isovolumetric (256 ± 46 vs. 200 ± 35 and 644 ± 36 vs. 511 ± 40 mL, respectively, P < 0.05) distensions. Cisapride significantly enhanced the size of the meal‐induced fundus relaxation (143 ± 37 vs. 270 ± 50 mL, P < 0.05). Conclusions: Cisapride enhances both the perception of gastric distension and the gastric accommodation to a meal. These data suggest that cisapride may provide benefit to patients with impaired postprandial relaxation of the fundus.