title: Role of Rho kinase and Na+/H+ exchange in hypoxia-induced pulmonary arterial smooth muscle cell proliferation and migration.
abstract: Abnormal proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) are hallmark characteristics of vascular remodeling in pulmonary hypertension induced by chronic hypoxia. In this study, we investigated the role of the Na(+)/H(+)exchanger (NHE) and alterations in intracellularpH(pHi) homeostasis in meditating increased proliferation and migration inPASMCs isolated from resistance-sized pulmonary arteries from chronically hypoxic rats or from normoxic rats that were exposed to hypoxia ex vivo (1% or 4% O2, 24-96 h). We found thatPASMCs exposed to either in vivo or ex vivo hypoxia exhibited greater proliferative and migratory capacity, elevated pHi, and enhancedNHEactivity. TheNHEinhibitor, ethyl isopropyl amiloride (EIPA), normalized pHiin hypoxicPASMCs and reduced migration by 73% and 45% in cells exposed to in vivo and in vitro hypoxia, respectively. Similarly,EIPAreduced proliferation by 97% and 78% in cells exposed to in vivo and in vitro hypoxia, respectively. We previously demonstrated thatNHEisoform 1 (NHE1) is the predominant isoform expressed inPASMCs. The development of hypoxia-induced pulmonary hypertension and alterations inPASMC pHihomeostasis were prevented in mice deficient forNHE1. We found that short-term (24 h) ex vivo hypoxic exposure did not alter the expression ofNHE1, so we tested the role of Rho kinase (ROCK) as a possible means of increasingNHEactivity. In the presence of theROCKinhibitor, Y-27632, we found that pHiandNHEactivity were normalized and migration and proliferation were reduced inPASMCs exposed to either in vivo (by 68% for migration and 22% for proliferation) or ex vivo (by 43% for migration and 17% for proliferation) hypoxia. From these results, we conclude that during hypoxia, activation ofROCKenhancesNHEactivity and promotesPASMCmigration and proliferation.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Walker
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Clark
authors.initials: C
authors.lastname: Undem
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Xin
authors.initials: X
authors.lastname: Yun
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Julie
authors.initials: J
authors.lastname: Lade
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland lshimod1@jhmi.edu.
authors.forename: Larissa A
authors.initials: LA
authors.lastname: Shimoda
mesh_terms: D000577:Amides / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D006976:Hypertension, Pulmonary / Q000201:enzymology / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D000860:Hypoxia / Q000150:complications* / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D011725:Pyridines / Q000494:pharmacology; D017208:Rats, Wistar; D015398:Signal Transduction; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D066253:Vascular Remodeling / Q000187:drug effects; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D000577:Amides; D027682:Cation Transport Proteins; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C490997:Slc9a1 protein, mouse; C452850:Slc9a1 protein, rat; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; C108830:Y 27632; D000584:Amiloride; D054460:rho-Associated Kinases; C039614:ethylisopropylamiloride
keywords: Pulmonary hypertension; remodeling; vascular