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Departments of 1Pediatrics, 2Physiology, 3Pathology, and 4Medicine, New York Medical College, Valhalla, New York
Submitted 20 February 2007 ; accepted in final form 1 April 2008
Monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) in rats is preceded by an inflammatory response, progressive endothelial cell membrane disruption, reduction in the expression of caveolin-1, and reciprocal activation of STAT3 (PY-STAT3). Superoxide and NF-
B have been implicated in PAH. To evaluate the role of caveolin-1, PY-STAT3 activation, and superoxide in PAH, MCT-injected rats were treated daily with pyrrolidine dithiocarbamate (PDTC; starting on days 1, 3, and 14 x 2 wk), an inhibitor of inflammation and NF-
B activation. Hemodynamic data, the expression of inhibitory (I)-
B
, caveolin-1, and Tie2 (a membrane protein), activation of PY-STAT3 and NF-
B, and superoxide chemiluminescence were examined. Rats developed progressive PAH at 2 wk post-MCT. There was progressive reduction in the expression of caveolin-1, Tie2, and activation of PY-STAT3 in the lungs. Reduction in I-
B
expression was present at 2 and 4 wk post-MCT. Superoxide chemiluminescence and NF-
B activation were observed only at 2 wk post-MCT and both decreased by 4 wk post-MCT despite progressive PAH. PDTC (starting on days 1 and 3) rescued caveolin-1 and Tie2, reversed MCT-induced PY-STAT3 activation, and attenuated PAH. In addition, PDTC restored I-
B
expression and reduced superoxide chemiluminescence at 2 wk but did not inhibit NF-
B activation despite attenuation of PAH. PDTC had no effect on established PAH. Increased superoxide chemiluminescence and NF-
B activation appear to be a transient phenomenon in the MCT model. Thus the disruption of endothelial cell membrane integrity resulting in caveolin-1 loss and reciprocal activation of PY-STAT3 plays a key role in the MCT-induced PAH.
caveolin-1; inhibitory
B
; inflammation; PY-STAT3; Tie2
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