Involvement of RhoA/Rho kinase signaling in pulmonary hypertension of the fawn-hooded rat.
The fawn-hooded rat (FHR) develops severe pulmonary hypertension (PH) when raised for the first 3-4 wk of life in the mild hypoxia of Denver's altitude (5,280 ft.). The PH is associated with sustained pulmonary vasoconstriction and pulmonary artery remodeling. Furthermore, lung alveolarization and vascularization are reduced in the Denver FHR. We have recently shown that RhoA/Rho kinase signaling is involved in both vasoconstriction and vascular remodeling in animal models of hypoxic PH. In this study, we investigated the role of RhoA/Rho kinase signaling in the PH of Denver FHR. In alpha-toxin permeabilized pulmonary arteries from Denver FHR, the contractile sensitivity to Ca2+ was increased compared with those from sea-level FHR. RhoA activity and Rho kinase I protein expression in pulmonary arteries of Denver FHR (10-wk-old) were higher than in those of sea-level FHR. Acute inhalation of the Rho kinase inhibitor fasudil selectively reduced the elevated pulmonary arterial pressure in Denver FHR in vivo. Chronic fasudil treatment (30 mg.kg-1.day-1, from birth to 10 wk old) markedly reduced the development of PH and improved lung alveolarization and vascularization in Denver FHR. These results suggest that Rho kinase-mediated sustained vasoconstriction, through increased Ca2+ sensitivity, plays an important role in the established PH and that RhoA/Rho kinase signaling contributes significantly to the development of PH and lung dysplasia in mild hypoxia-exposed FHR.
Nagaoka
Tetsutaro
T
CVP Research Laboratory, Department of Medicine, B-133, UCDHSC, 4200 East Ninth Ave., Denver, CO 80262, USA.
Gebb
Sarah A
SA
Karoor
Vijaya
V
Homma
Noriyuki
N
Morris
Kenneth G
KG
McMurtry
Ivan F
IF
Oka
Masahiko
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000531:Altitude; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D006439:Hemodynamics / Q000187:drug effects; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D017380:Hypertrophy, Right Ventricular / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000473:pathology; D011651:Pulmonary Artery / Q000737:chemistry / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction; D014661:Vasoconstriction / Q000187:drug effects; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; C049347:fasudil; D002118:Calcium