Affiliation:
1. Department of Physiology, College of Medicine, University of Arizona, Tucson 85724.
Abstract
In eight anesthetized New Zealand White rabbits, the aorta was cannulated in situ for measurement of hydraulic conductance (Lp) at different pressures with and without endothelium. De-endothelialization increased Lp at > or = 75 mmHg but not at 50 mmHg. Because endothelium resists transmural water flow, the endothelium must also increase medial Lp at 50 mmHg. To determine whether this effect results from secretion of endothelial-derived relaxing factor (EDRF), Lp was measured in eight rabbits in the presence and absence of NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of EDRF synthesis. At 50 mmHg L-NAME reduced Lp from 6.79 +/- 2.19 to 2.59 +/- 1.41 (SD) x 10(-8) (P < 0.05, paired Student's t test). After L-NAME was removed, Lp returned to its control value. At 125 mmHg L-NAME did not significantly change Lp, although endothelial permeability seemed to increase. L-NAME did not affect Lp of nine de-endothelialized vessels at either pressure. An additional five experiments showed that the effect of L-NAME at 50 mmHg was reversed by L-arginine. Eleven additional experiments demonstrated that NG-nitro-D-arginine methyl ester does not affect Lp at 50 mmHg. These results indicate that EDRF increases Lp of the rabbit aorta at low pressures.
Publisher
American Physiological Society
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine,Physiology
Cited by
32 articles.
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