title: Inhibition of Rho-kinase attenuates hypoxia-induced angiogenesis in the pulmonary circulation.
abstract: Pulmonary hypertension (PH) is a common complication of chronic hypoxic lung diseases, which increase morbidity and mortality. Hypoxic PH has previously been attributed to structural changes in the pulmonary vasculature including narrowing of the vascular lumen and loss of vessels, which produce a fixed increase in resistance. Using quantitative stereology, we now show that chronic hypoxia caused PH and remodeling of the blood vessel walls in rats but that this remodeling did not lead to structural narrowing of the vascular lumen. Sustained inhibition of the RhoA/Rho-kinase pathway throughout the period of hypoxic exposure attenuated PH and prevented remodeling in intra-acinar vessels without enlarging the structurally determined lumen diameter. In chronically hypoxic lungs, acute Rho kinase inhibition markedly decreased PVR but did not alter the alveolar to arterial oxygen gap. In addition to increased vascular resistance, chronic hypoxia induced Rho kinase-dependent capillary angiogenesis. Thus, hypoxic PH was not caused by fixed structural changes in the vasculature but by sustained vasoconstriction, which was largely Rho kinase dependent. Importantly, this vasoconstriction had no role in ventilation-perfusion matching and optimization of gas exchange. Rho kinase also mediated hypoxia-induced capillary angiogenesis, a previously unrecognized but potentially important adaptive response.
authors.affiliation: Department of Physiology, University College, Earlsfort Terrace, Dublin 2, Ireland.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Hyvelin
authors.forename: Katherine
authors.initials: K
authors.lastname: Howell
authors.forename: Alistair
authors.initials: A
authors.lastname: Nichol
authors.forename: Christine M
authors.initials: CM
authors.lastname: Costello
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Preston
authors.forename: Paul
authors.initials: P
authors.lastname: McLoughlin
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002196:Capillaries / Q000187:drug effects / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006976:Hypertension, Pulmonary / Q000209:etiology* / Q000517:prevention & control; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D047908:Intracellular Signaling Peptides and Proteins; D008168:Lung / Q000098:blood supply*; D008297:Male; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000032:analysis
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; D042461:Vascular Endothelial Growth Factor A; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein