The influence of copper on the in vitro motility of the human Fallopian tube.

Experiments were designed to examine whether one contraceptive action of the copper intrauterine contraceptive devices (Cu-IUD's) could be associated with an influence on the smooth muscle activity of the Fallopian tube. Sections of the isthmic portion of human oviducts were removed during operation. Preparations from the circular muscle layer were mounted for isometric recording of contractile activity. Subsequently, spontaneous rhythmic contractions appeared within one to five minutes after the preparation procedure was completed. Transmural nerve stimulation or addition of norepinephrine or prostaglandin F2alpha to the Tris buffer medium caused an increase in tone and frequency. Addition of CuCl2 caused a concentration-dependent increase in frequency and a concomitant decrease in amplitude. High concentrations of CuCl2 produced a marked initial increase in frequency, but the rhythmic activity was soon abolished. Metallic copper in the incubation medium caused the same qualitative effects on the smooth muscle preparation as CuCl2. Influences of copper on contractions of rat portal vein preparations were studied in the same way, and similar effects were found. The copper concentration of the secretion in the Fallopian tube was measured by atomic absorption in seven patients wearing CU-IUD's until operation. The levels found were of the same order of magnitude as the concentration of free copper ions which in vitro caused effects on the smooth muscle. It is concluded that copper can affect smooth muscle activity. An influence of copper on the motility of the human oviduct has to be considered as a possible factor contributing to the contraceptive action of the Cu-IUD.