5-Hydroxytryptamine receptor antagonism by metoclopramide and ICS 205-930 in the guinea-pig leads to enhancement of contractions of stomach muscle strips induced by electrical field stimulation and facilitation of gastric emptying in-vivo.

Contractions induced by electrical field stimulation of isolated circular muscle strips, taken from the guinea-pig stomach, were enhanced by metoclopramide, ICS 205-930 and MDL 72222 at concentrations similar to those shown to antagonize at neuronal 5-hydroxytryptamine receptor sites in a variety of preparations. Metoclopramide, MDL 72222 and ICS 205-930 also facilitated gastric emptying in-vivo. The abilities of metoclopramide, MDL 72222 and ICS 205-930 to enhance stomach muscle contraction processes and to facilitate gastric emptying may be the consequence of 5-hydroxytryptamine receptor antagonism.