RT Journal Article SR Electronic T1 THE EFFECTS OF OVARIAN EXTRACTS UPON ACTIVITY OF THE GUINEA PIG UTERUS IN SITU JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 160 OP 164 VO 107 IS 2 A1 Lloyd C. Felton A1 Harold H. Bryant A1 Edward H. Frieden YR 1953 UL http://jpet.aspetjournals.org/content/107/2/160.abstract AB Studies of the chemical properties of a uterine relaxing factor (URF), obtained from aqueous extracts of sows' ovaries indicate that the active agent is non-dialyzable, stable to heat, and sensitive to the action of proteolytic enzymes and a variety of reducing agents. It is concluded that URF is a protein or polypeptide. URF activity is also displayed by both crude and purified relaxin preparations, and comparison of the occurrence of URF and relaxin in various tissues suggests a close relationship between the two substances. The possible relationship of protein-like hormones of the reproductive tract to changes in uterine motility have been discussed.