THE ENHANCEMENT OF RELAXTN-INDUOED GROWTH OF THE PUBIC LIGAMENT IN MICE1

Abstract
Using the x-ray measurement of interpubic distance as an assay procedure, it was found that purified relaxin which is of low potency in mice can be enhanced in activity by delaying its absorption from the site of injection. Of the depot media and binding agents which were tested, the most effective was a suspension of lyophilized relaxin in 5% beeswax and oil, which produced a 65-fold increase in assay potency. In contrast, the mouse-active fraction of sow ovaries, which is notabty less soluble than relaxin, was not potentiated by the depot medium. It was therefore concluded that the growth response of the pubic ligament can be obtained with depot relaxin, and that the mouse-active fraction represents a more slowly mobilized form of relaxin. The relationship of these findings to the interpretation of bioassay data was discussed, and a modified procedure was suggested to provide a quantitative assay of relaxin in mice.