DUAL EFFECTS OF TRIMEBUTINE ON ELECTRICAL RESPONSES OF GASTRIC SMOOTHMUSCLES IN THE RAT

The effects of trimebutine on the electrical properties of smooth musc le membranes were studied in the isolated rat stomach, the objective b eing to elucidate the dual actions of this drug on gastric motility. T ransmural nerve stimulation elicited a cholinergic excitatory junction potential (e.j.p.) and a nonadrenergic noncholinergic inhibitory junc tion potential (i.j.p.), and trimebutine inhibited the e.j.p. more tha n the i.j.p., with no significant change in the acetylcholine-induced depolarization. Trimebutine reduced the interval and, at high concentr ations, the amplitude of slow waves. In enzymatically dispersed single cells, the Ca2+ current elicited by depolarization of the membrane wa s also inhibited by trimebutine. Thus, trimebutine increases slow wave frequency and inhibits cholinergic transmission and Ca2+ influx. The former would enhance while the latter two would depress gastric motili ty.