Effects of chlorpromazine and the antidepressant drugs amitriptyline, clomipramine and mianserin on the Ca-depleted rat uterus.

We have investigated the effect of three antidepressants and one phenothiazine on the EDTA-treated rat uterus. It was found that these drugs induce a sustained contraction of tissue in a Ca-free medium (called Ca-free contraction) at concentrations between 5 X 10(-5) and 1 X 10(-4) M. These responses allowed the construction of dose-response curves. However, higher concentrations caused a relaxation of strips contracted by lower doses previously applied. Oxytocin 1 X 10(-2) IU/ml accelerates the appearance of this relaxation. The antidepressants and chlorpromazine at high doses inhibit the oxytocin-induced Ca-free contraction. The drugs-induced Ca-free contraction could be repeated in the same preparation with only a slight reduction in magnitude.