Effect of ergometrine on contractile force of guinea-pig isolated heart: antagonism by cimetidine.

The action of ergometrine on contractile force of guinea-pig isolated heart was investigated and the effect of receptor antagonists on the inotropic effect of ergometrine, isoproterenol, dopamine and histamine was evaluated. Ergometrine was found to have a good dose-dependent inotropic effect and the antagonism of cimetidine toward this action is reported. Experiments carried out in hearts in which a massive depletion of mast-cells histamine was produced are in favour of a direct action of the drug on H2-receptors.