(Hypertension. 2008;51:867.)
© 2008 American Heart Association, Inc.
Original Articles |
Signaling Causes Cerebral Vascular Dysfunction, Hypertrophy, and RemodelingFrom the Genetics Graduate Program (A.M.B., C.M.H.), the Department of Pathology (G.L.B., T.D.G., S.M.G.), the Department of Internal Medicine (M.L.M., C.M.L., W.J.d.L., H.L.K., C.D.S., F.M.F.), the Department of Molecular Physiology and Biophysics (C.D.S.), the Center on Functional Genomics of Hypertension (C.D.S.), and the Department of Pharmacology (F.M.F.), Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City; and the Department of Pathology (Y.-S.T., N.M.), University of North Carolina, Chapel Hill.
Correspondence to Frank M. Faraci, PhD, Department of Internal Medicine, E318-2 GH, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242. E-mail frank-faraci{at}uiowa.edu or Curt D. Sigmund, PhD, Departments of Internal Medicine and Physiology & Biophysics, 3181B MERF, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242. E-mail curt-sigmund@uiowa.edu
The transcription factor PPAR
is expressed in endothelium and vascular muscle where it may exert antiinflammatory and antioxidant effects. We tested the hypothesis that PPAR
plays a protective role in the vasculature by examining vascular structure and function in heterozygous knockin mice expressing the P465L dominant negative mutation in PPAR
(L/+). In L/+ aorta, responses to the endothelium-dependent agonist acetylcholine (ACh) were not affected, but there was an increase in contraction to serotonin, PGF2
, and endothelin-1. In cerebral blood vessels both in vitro and in vivo, ACh produced dilation that was markedly impaired in L/+ mice. Superoxide levels were elevated in cerebral arterioles from L/+ mice and responses to ACh were restored to normal with a scavenger of superoxide. Diameter of maximally dilated cerebral arterioles was less, whereas wall thickness and cross-sectional area was greater in L/+ mice, indicating cerebral arterioles underwent hypertrophy and remodeling. Thus, interference with PPAR
signaling produces endothelial dysfunction via a mechanism involving oxidative stress and causes vascular hypertrophy and inward remodeling. These findings indicate that PPAR
has vascular effects which are particularly profound in the cerebral circulation and provide genetic evidence that PPAR
plays a critical role in protecting blood vessels.
Key Words: endothelial function dominant negative hypertension remodeling hypertrophy
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