5-Hydroxytryptamine can antagonize the ability of metoclopramide and SCH 23390 to enhance electrical field stimulation-evoked contractions of guinea-pig isolated stomach muscle

Electrical field stimulation of guinea-pig stomach strips caused frequency related contractions that were enhanced by metoclopramide and SCH 23390 (10(-7)-10(-5) M) and antagonized by atropine (5 X 10(-8) M. 5-HT (3 X 10(-8)-3 X 10(-5) M) antagonized the ability of metoclopramide and SCH 23390 to enhance the contractions. It is concluded that metoclopramide and SCH 23390 can enhance electrical field stimulation-induced contractions in the stomach strips by a 5-HT receptor blockade which can facilitate cholinergic mediated contractions.