Venous Bradykinin-Antagonistic Property of Estrogen

Abstract

Using a single segment of rabbit saphenous vein preparation in vitro a perfusion experiment with Locke-Ringer's solution (pH 7.2, 37°C) has been performed. The venoconstrictive effect of bradykinin, which was injected into the perfusate, was recorded as the decrease of the outflow from the preparation and recorded by dorp counter. A consistent and dose dependent venoconstriction was induced by bradykinin and there was no tachyphylaxis.
The conjugated estrogens from the urine of pregnant hourses (Premarin) exhibited a potent antibradykinin activity on the venoconstrictive effect of bradykinin and the potency of bradykinin, the control being 1.0, was reduced by combination of Premarin at concentration of 50μg per ml and 100μg per ml to 0.651 and 0.431 respectively. The washability of Premarin is good. The dose response curves of bradykinin obtained under the perfusion with Locke-Ringer's solution and those obtained under the perfusion of Premarin solution were practically parallel, being the slope 75.8° and the index of precision 0.228.