EFFECT OF HEPARIN ON THE VASOCONSTRICTOR ACTION OF SHED BLOOD TESTED BY PERFUSION OF THE RABBIT'S EAR

Abstract

Defibrinated blood as a perfusion fluid induces marked vaso-constriction in the surviving ear of the rabbit. Heparinized blood was moderately constrictor. Perfusion of the rabbit''s ear could be accomplished with less progressive constriction by injecting heparin into the donor rabbit to arrest coagulation at an early stage before the blood was withdrawn. Precautions against cooling of the ear were also essential for consistent results. Small amts., 0.2 cc, of defibrinated blood and serum from normal rabbits, dogs and human beings induce marked constriction. Heparinized or "pre-heparinized" whole blood is much less constrictor but still too variable to be useful in assays. Plasma rapidly separated from heparinized or "pre-heparinized" blood of normal rabbits, dogs and human beings has little or no vasoconstrictor activity. These studies emphasize the importance of excluding coagulation when the rabbit''s ear method is used to detect constrictor substances of renal or other origin in the circulating blood.