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Atherosclerosis and Lipoproteins |
From the Graduate Center for Nutritional Sciences (L.A.C., A.D.) and the Cardiovascular Research Center (D.L.R., H.L., A.D.), University of Kentucky, Lexington.
Correspondence to Alan Daugherty or Lisa Cassis, Wethington Building, Room 521, University of Kentucky, Lexington, KY 40536-0200. E-mail Alan.Daugherty{at}uky.edu or cassis@uky.edu
Objective Angiotensin II (AngII) infusion into hypercholesterolemic mice accelerates atherosclerosis and promotes formation of abdominal aortic aneurysms (AAAs). The purpose of this study was to define whether AngII interacts with receptors on infiltrating versus resident cells in promoting vascular pathologies.
Methods and Results Male LDL receptor/ mice, that were either AT1a receptor +/+ or /, were fed a fat enriched diet and infused with either saline or AngII. AngII-induced augmentation of atherosclerosis and formation of AAAs was ablated in AT1a receptor/ mice. Bone marrow transplantation studies were performed to determine the role of AT1a receptors expressed on infiltrating cells. AT1a receptor +/+ and / mice were irradiated and repopulated with bone marrowderived stem cells of either genotype. These 4 groups of chimeric mice were infused with either saline or AngII. Repopulation of irradiated AT1a receptor +/+ mice with / bone marrowderived cells resulted in modest reductions in AngII-induced atherosclerosis. Unexpectedly, AT1a receptordeficient recipient mice were dramatically protected from AngII-induced vascular pathologies, irrespective of donor genotype.
Conclusion AngII promotes vascular pathology via AT1a receptors. AT1a receptors expressed on infiltrating cells exert modest regulation of AngII-induced atherosclerosis. However, the presence of this receptor in resident tissue is required for the initiation of AngII-induced atherosclerosis and AAAs.
AngII infusion into hyperlipidemic mice leads to augmentation of atherosclerosis and formation of AAAs. The absence of AT1a receptors ablated the development of both these pathologies. Bone marrow transplantation studies demonstrated that the AT1a receptor genotype of the recipient was required to initiate these vascular diseases.
Key Words: angiotensin receptors atherosclerosis aneurysms
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