[Comparative study on the action of some substituted benzamides on the isolated ileum of the guinea pig].

Metoclopramide [(Mcp)-N-diethylaminoethyl-2-methoxy-4-amino-5-chloro-benzamide] was shown by the authors (This Journal 1973, 204, 239) to stimulate the isolated guinea-pig ileum, mainly by an indirecr cholinergic mechanism, to increase responses to acetylcholine (Ac) and transmural stimulation, and to inhibit responses to serotonin (5 HT) and histamine (H). Four structuraly related benzamide derivative (1211, 1265, 1308 and 1347) also stimutated the ileum, 1211 being the most active, and 1347 the least active, and resembled Mcp with regard to the responses to Ac, transmural stimulation and histamine. However, serotonin contractions were enhance by 1265 and 1347, while 1308 and 1211 were inhibitory. These observations suggest that a 4-amino group does not seem to be essential for the stimulant effect or the interference with Ac responses (1211, 1265, 1347), whereas a methylsulfonyl group (1347) and, to a lesser degree, a flour in 5 position (1265) sensitize the ileum towards 5 HT contractions.