The Inhibitory Effects of Felodipine, Verapamile, Nimodipine and Nicardipine on The Contractile Response to Acetylcholine in Isolated Rat Gastro-esophageal Sphineter

In this in vitro study, the dilatory effects of felodipine, verapamile, nimodipine and nicardipine on the contractile response to acetylcholine in isolated rat esophageal splıincter were investigated. The ga,s-tro-esophageal sphincters, obtained from rats, were suspended in Krebs-lIenseleit solution and were contracted with 10-4 M acetylcholine. In this part of investigation, cumulative concentrations (10-9-10-4M) of one of the antagonists were added in the medium. Then the responses were observed. tn the other part of investigation, cumulative concentrations of the same antagonist were applied on the preparation, which was contracted with acetylcholine in the Ca2+ -free medium. The maximuın contraction response induced by acetylcholine in Ca2+ -free medium was simi lar ta the response, obtained in medium with Ca2 . It was showed that, acetylcholine used both intra-and extracellular Ca2+. The poıency of the inhibitory effects of these calcium channel blockers was felodipine>verapamile>nimodipine=nicardipine. In Ca2+-free medium, there was no inhibition. The re,s-ults suggest that, these calcium channel blockers are effective on gastro-esophageal sphincter contractions and may be tıseful in the treatment of esophageal spasm.