RESPONSIVENESS OF ISOLATED DOG VEINS TO BRADYKININ: DISTRIBUTION AND A POSSIBLE CORRELATION WITH GENESIS OF THE VENOUS SYSTEM

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Abstract
Several vasoactive substances such as Ne [norepinephrine], ACh [acetylcholine], histamine, 5-HT [5-hydroxytryptamine, serotonin], angiotensin II and BK [bradykinin] were tested in dogs. NE induced the largest contraction in almost all preparations obtained from various sites of the venous system. The contraction produced by NE was taken as standard, the effects of BK were compared. The ED50 values of veins for NE ranged from 1.0 .times. 10-7 M (portal vein) to 1.3 .times. 10-6 M (posterior vena cava between the liver and the renal veins.) Dose-dependent contractions were clearly observed in pulmonary, hepatic, portal, splenic veins, anterior vena cava and 2 divisions of posterior vena cava (proximal to the diaphragm and between the liver and the renal veins). The response to BK exceeded that to NE only in the supradiaphgram division of posterior vena cava. The response of cephalic, external jugular, azygos, femoral, lateral saphenous veins and posterior vena cava (distal to the renal veins) was very low. Maximun contractions induced by 10-5 M BK were less than 5% of that by NE. Renal veins showed individually different responses. The veins can be classified into 2 groups, 1 group includes veins highly sensitive to BK such as those in the visceral area, and the other group those veins which have a low sensitivity to BK such as those in extremities and the body wall. Renal veins appear to be of an intermediate nature.

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