Effect of strophantin on the isolated guinea-pig ileum

The effect of strophantin on isolated guinea-pig ileum was investigated. It was found that strophantin produces a dose-dependent contraction that is not blocked by atropine, ganglionic blockade, but is potentiated by prostigmine. Depolarization of the guinea-pig ileum by a high potassium solution does not change the effect of strophantin. Strophantin response is competitively antagonized by verapamil. The effect is significantly reduced, 5 to 10 min, after the preparation is immersed in zero calcium Tyrode solution. These results support the view that the effect of strophantin is dependent on the influx of calcium through the cell membrane.