Dose response relationship of relaxin on the pubic ligament of the mouse

In the present work, the dose-response relationship of highly purified porcine relaxin has been examined on broadening of the pubic ligament in mice. Using the method of Steinetz et al. with 7 days of oestriol priming, higher sensitivity of the pubic ligament was attained in mice with an original weight of 10 g than in those with a weight of 20 g. S-shaped curves were obtained; by increasing the relaxin doses after maximal effect had been reached a decreased action was observed. With presomen priming, a relaxin effect was established after only 2 days instead of the usual 8 days but the action was markedly less than in the Steinetz test.