AJP - Heart and Circulatory Physiology, Vol 250, Issue 5 892-H897, Copyright © 1986 by American Physiological Society
Enhanced adrenergic constriction of iliac artery with removal of endothelium in conscious dogs
M. A. Young and S. F. Vatner
We studied, in conscious dogs, the effects of removal of endothelium on the
responses of iliac artery diameter and iliac blood flow to intra-arterial
infusions of adrenergic agonists. With endothelium intact, iliac diameter
increased with intra-arterial infusion of nitroglycerin (4.7 +/- 0.4%),
acetylcholine (4.2 +/- 0.6%), and epinephrine (4.5 +/- 1.3%), and decreased
with norepinephrine (-7.5 +/- 1.7%), phenylephrine (-6.6 +/- 1.0%), and
B-HT 920 (-2.1 +/- 0.6%). One- to-five days following removal of
endothelium with a balloon-tipped catheter, base-line iliac diameter was
unchanged, and still increased with nitroglycerin (4.6 +/- 0.5%), but not
with acetyl-choline, and epinephrine actually decreased diameter (-3.5 +/-
1.3%). Removal of the endothelium also enhanced the constriction observed
with norepinephrine (-12.5 +/- 2.0%) and phenylephrine (-11.4 +/- 1.6%),
but not with B-HT 920 (-1.8 +/- 0.5%). The changes in arterial pressure,
iliac blood flow, iliac vascular resistance, and heart rate induced by any
of the agonists did not differ before and after removal of the endothelium.
These results indicate that the endothelium mediates the dilation in
response to epinephrine and also serves an important role in protecting
against alpha 1-adrenergic vasoconstriction of large iliac arteries.
