Formation and Breakdown of Collagen and Elastin in the Human Uterus during Pregnancy and Post-partum Involution.

acrylamide gel. A highly active substance was isolated by ion-exchange chromatography on a 5 % cross-linked polymer ofacrylamide, NN'-methylenebisacrylamide and diethylaminoethyl methacrylate. 2. The initial gel-filtration experiments were carried out under a wide variety of conditions and resulted in the same yield of high-molecularweight and low-molecular-weight fractions with inotropic activity. 3. It was concluded that it was unlikely that the low-molecular-weight fraction with inotropic activity was an artifact produced from the plasma proteins by the method of isolation. 4. The inotropic activity of the isolated substance was destroyed by incubation with protease. The authors acknowledge the technical assistance of Miss S. Freame and Miss J. Harris. They are also indebted to Mr S. Hart and Mr J. Bremner for advice on and help with the construction of chromatographic apparatus.