[The effect of sexual steroids on the isometric contraction of the isolated rat diaphragm (author's transl)].

The influence of estradiolbenzoate, hydroprogesteroncapronate and pregnancy on the mechanical reaction of the directly and indirectly stimulated nerve-diaphragm preparation has been the subject of this investigation. Rats were ovario-ectomized and the hormone preparations were injected subcutaneously. After a lapse of 9 days the test preparation was made. 1. Estrogen and the estrogen-gestagen combination have a similar effect on the isometric contraction of the transversely striated muscle. The times of rising and relaxation were prolonged after indirect and direct stimulation. The contraction amplitude had not altered compared to the control group. 2. Gestagens and the hormone situation of pregnancy entail, independent of the kind of stimulation, a decrease of the tension progress and the speed of the tension increase. The gestagen-treated animals underwent a shortened contraction process. These findings enable us to comment on the different efficiencies of women during various cycle phases and during pregnancy.