An Ether-Extractable Substance from Blood Serum and Buffy Goat Which Contracts Smooth Muscle.

SummaryA substance which stimulates smooth muscle was separated from dried rabbit serum and from the buffy coat of human blood by ether extraction. This substance is soluble in ether only in the presence of certain blood lipids. Aqueous solutions of the material stimulate the rat and rabbit intestine, cat nictitating membrane and tail vessels, but are devoid of effect on the vessels of the rabbit ear. The present findings, together with those of Tsai et al.,7 suggest that several vasoconstrictor substances are present in serum.