A smooth muscle contracting substance in extracts of human umbilical cord

Abstract

Aqueous extracts of human umbilical arteries and vein have been shown to contain a smooth muscle contracting substance. The active principle has been distinguished from smooth muscle contracting substances which are found in mammalian tissues, namely esters of choline, histamine, 5-hydroxytryptamine, bradykinin, angiotensin, and darmstoff. Evidence indicates that the smooth muscle stimulating activity of umbilical blood vessel extracts is due to a lipid-soluble unsaturated hydroxy acid. The possible physiological function of the active substance is discussed.