Angiotensin-converting enzyme inhibitor preserves p21 and endothelial nitric oxide synthase expression in monocrotaline-induced pulmonary arterial hypertension in rats.
BACKGROUND
Pulmonary arterial hypertension (PAH) is associated with structural changes in the pulmonary vasculature characterized by the proliferation of cellular components of the vessels. ACE inhibitor (ACEI) may have beneficial effects in treating PAH, but its precise mechanism of action in the remodeling process is unclear. p21 is a cyclin-dependent kinase inhibitor that may have a protective role in this process by inhibiting cellular proliferation. Endothelial nitric oxide synthase (eNOS) has also been shown to be protective by its vasodilatory effect. Therefore, we investigated whether expression of p21 and eNOS was modulated by ACEI treatment in a rat model.


RESULTS
Monocrotaline (MCT) was administered to 2 groups of Sprague-Dawley rats fed a high-cholesterol diet, ie, one group received MCT concomitantly with enalapril treatment (MCT(+)/ACEI(+) rats), and the other group did not receive enalapril (MCT(+)/ACEI(-) rats). After 5 weeks, MRI showed right ventricular hypertrophy in MCT(+)/ACEI(-) rats. MCT(+)/ACEI(+) rats showed a preserved right ventricular morphology. Isolated pulmonary perfusion studies showed that ACEI significantly upregulated NO production, as measured by nitrite levels. Addition of N-methyl-D-glucamine dithiocarbamate-Fe solution, an NO-trapping agent, reversed the basal vasodilatory effect of ACEI in the pulmonary vasculature. Immunoblot analysis showed decreased p21 and eNOS expression in the lung in MCT(+)/ACEI(-) rats, whereas their expression was preserved with enalapril treatment.


CONCLUSIONS
ACEI suppresses the development of MCT-induced PAH in rats. The mechanism of action might involve the preservation of p21 and eNOS expression. Both p21 and endothelium-derived NO appear to have protective roles in the development of PAH.
Kanno
S
S
Department of Biological Sciences and Pittsburgh NMR Center for Biomedical Research, Carnegie-Mellon University, Pittsburgh, PA 15213-2683, USA. skanno@andrew.cmu.edu
Wu
Y J
YJ
Lee
P C
PC
Billiar
T R
TR
Ho
C
C
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D004041:Dietary Fats; D004195:Disease Models, Animal; D004656:Enalapril / Q000494:pharmacology; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D017380:Hypertrophy, Right Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D016686:Monocrotaline; D009566:Nitrates / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D010477:Perfusion; D011651:Pulmonary Artery / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
D000806:Angiotensin-Converting Enzyme Inhibitors; C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004041:Dietary Fats; D009566:Nitrates; D020030:Nitric Oxide Donors; D009573:Nitrites; D004656:Enalapril; D016686:Monocrotaline; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat