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Patchy deletion of Bmpr1a potentiates proximal pulmonary artery remodeling in mice exposed to chronic hypoxia.
MedLine Citation:
PMID:  22314711     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Reduced vascular expression of bone morphogenetic protein type IA receptor (Bmpr1a) has been found in patients with pulmonary arterial hypertension. Our previous studies in mice with patchy deletion of Bmpr1a in vascular smooth muscle cells and cardiac myocytes showed decreased distal vascular remodeling despite a similar severity of hypoxic pulmonary hypertension (HPH). We speculate increased stiffness from ectopic deposition of collagen in proximal pulmonary arteries might account for HPH. Pulsatile pressure-flow relationships were measured in isolated, ventilated, perfused lungs of SM22α;TRE-Cre;R26R;Bmpr1a ( flox/flox ) (KO) mice and wild-type littermates, following 21 days (hypoxia) and 0 days (control) of chronic hypoxia. Pulmonary vascular impedance, which yields insight into proximal and distal arterial remodeling, was calculated. Reduced Bmpr1a expression had no effect on input impedance Z (0) (P = 0.52) or characteristic impedance Z (C) (P = 0.18) under control conditions; it also had no effect on the decrease in Z (0) via acute rho kinase inhibition. However, following chronic hypoxia, reduced Bmpr1a expression increased Z (C) (P < 0.001) without affecting Z (0) (P = 0.72). These results demonstrate that Bmpr1a deficiency does not significantly alter the hemodynamic function of the distal vasculature or its response to chronic hypoxia but larger, more proximal arteries are affected. In particular, reduced Bmpr1a expression likely decreased dilatation and increased stiffening in response to hypoxia, probably by collagen accumulation. Increased PA stiffness can have a significant impact on right ventricular function. This study illustrates for the first time how proximal pulmonary artery changes in the absence of distal pulmonary artery changes contribute to pulmonary arterial hypertension.
Authors:
Rebecca R Vanderpool; Nesrine El-Bizri; Marlene Rabinovitch; Naomi C Chesler
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-8
Journal Detail:
Title:  Biomechanics and modeling in mechanobiology     Volume:  -     ISSN:  1617-7940     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101135325     Medline TA:  Biomech Model Mechanobiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Biomedical Engineering, University of Wisconsin-Madison, 2146 Engineering Centers Building, 1550 Engineering Drive, Madison, WI, 53706, USA.
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