The effect of ondansetron on gastric emptying in the conscious rat.

The 5-HT3 receptor antagonist ondansetron (GR38032F) enhanced the action of a protein-rich solution in delaying gastric emptying in the conscious gastric fistula rat, but had no effect on the emptying of isotonic or hypertonic saline, acid or FOY-305 which delays emptying by release of cholecystokinin (CCK). The specific CCK-A antagonist (L-364,718) increased gastric emptying of protein-rich meals. L364,718 also increased emptying in the presence of ondansetron. They indicate that protein-rich meals release both CCK and 5-hydroxytryptamine which act in different ways to control gastric motility.