Cholesterol feeding enhances the vasoconstrictor effects of
products from rabbit polymorphonuclear leukocytes.
Hart, Joanne L., Christopher G. Sobey, and Owen L. Woodman.
Department of Pharmacology, University of Melbourne, Parkville,
Victoria, Australia 3052.
APStracts 2:0046H, 1995.
We have studied the vasoactive properties of products released from
rabbit polymorphonuclear leukocytes (PMNs) before and after short
term (4 and 8 weeks) dietary supplementation with 1% cholesterol.
Plasma cholesterol levels were similar after 4 and 8 weeks of
cholesterol diet, whilst gross atherosclerotic lesions were present
at 4 weeks but significantly more extensive after 8 weeks. PMN
products from all rabbits caused endothelium-dependent contraction of
isolated, control (non-atherosclerotic) rabbit aorta submaximally
contracted with phenylephrine. However, both 4 and 8 weeks of
cholesterol feeding resulted in equivalent contractions by PMN
products, which were significantly greater than contractions by
control PMNs. Endothelium-dependent contraction (by PMN products) and
relaxation (by acetylcholine) were attenuated by 8 weeks of
cholesterol feeding. PMN products attenuated acetylcholine-induced
relaxation of aorta from cholesterol-fed rabbits and of control aorta
treated with phenoxybenzamine to reduce muscarinic receptor reserve.
We conclude that elevation of plasma cholesterol results in increased
release of a PMN product(s) that causes endothelium-dependent
constriction.
Received 23 November 1994; accepted in final form 7 February
1995.
APS Manuscript Number H1040-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.