Effect of methylergometrine maleate (methergin) on electrical and mechanical activities of pregnant human myometrium.

The effect of methylergometrine maleate (methergin) on electrical and mechanical activities of pregnant human isthmic myometrium was examined. Methergin (10(-8)-10(-6) g/ml) enhanced plateau potential and contraction, however, the effects were not prominent. Plateau potential and contraction were also potentiated after pretreatment with 10(-7) g/ml phentolamine (alpha-blocker), however 10(-7) g/ml methergin further increased these effects. It is suggested that methergin might potentiate contractions by changing the pattern of action potentials and not by alpha-adrenoceptor.