Potencies of porcine relaxins using two bioassays

Relaxin reference preparations NIH-R-P1 and Warner Lambert W1164-3, and purified relaxin peptides, CM-a', CM-a and CM-B, were assayed in the mouse interpubic ligament and rat uterine inhibition bioassays. There was evidence that CM-a and CM-B would bind to glass and significant apparent increases in potency in the case of these two peptides alone resulted from the use of silicone-coated glassware. Using treated glassware, CM-a', CM-a and CM-B were equipotent in the mouse interpubic ligament bioassay with potencies relative to NIH-R-P1 of 3.97-, 4.85- and 3.64-fold respectively. In the rat uterine inhibition bioassay only W1164-3 and CM-a' gave dose-response curves which were parallel to NIH-R-P1. In this bioassay, potencies relative to NIH-R-P1 for W1164-3 and CM-a' were 0.35- and 19.6-fold respectively.