A simple biological assay for relaxin measurement

1. Relaxin (R) is considered a gestation hormone with an insulin-like molecular structure. Its physiological importance is significant in the reproduction process. 2. Different methods of biologically assaying R have been published but electrophysiology techniques on uterus and ileum of rat have never been used. 3. A protein fraction was obtained from ovarian tissue of the rat and used to measure electrophysiological activity in vivo and in vitro. 4. Protein recovered with R activity was similar to that in previous reports. 5. Reduction of 100% in contraction strength and 50% in its frequency was observed in ileum and in uterus respectively; it was only of 60%, but its frequency increased 43%. 6. Methodological considerations and some physiological aspects are discussed.