Effects of copper and zinc on rat uterine muscle contraction and rabbit blastocyst fluid accumulation

Abstract

The effect of copper and zinc on the isometric contractility of isolated rat uterine muscle has been studied. Results show that concentrations of 2 x 10-5 M Cu++ produce a drastic potentiating effect on the contraction, elicit spontaneous contractile activity, and at concentrations higher than 8 x 10-5 M, produce spasmodic contracture of the muscle. Effects of Cu++ are reversible. Zinc, at concentrations of 2 to 4 x 10-5 M has a marked depressant effect on rat uterine contractility. Although the effect of Zn++ is not reversed by washing under our experimental conditions, Cu++ in equivalent concentrations can reverse the depressant effect of Zn++. The potentiating effect of Cu++ is not modified by Zn++ at equimolar concentrations. Rabbit blastocyst fluid accumulation is not altered by 2 to 5 x 10-5 M Cu++ or Zn++ concentrations. However, long-term incubation (>1 h) in solution containing 5 x 10-5 M Cu++ results in complete degeneration of the embryo. The relevance of these results in relation to decreased expulsion rate and increased contraceptive effect of CuTIUD is discussed.