title: Rho/Rho kinase signaling mediates increased basal pulmonary vascular tone in chronically hypoxic rats.
abstract: Recent evidence suggests that Rho/Rho kinase signaling plays an important role in the sustained vasoconstriction induced by many agonists and is involved in the pathogenesis of systemic vascular diseases. However, little is known about its role in increased vascular tone in hypoxic pulmonary hypertension (PH). The purpose of this study was to examine whether Rho/Rho kinase-mediated Ca2+ sensitization contributed to sustained vasoconstriction and increased vasoreactivity in hypoxic PH in rats. Acute intravenous administration of Y-27632, a Rho kinase inhibitor, nearly normalized the high pulmonary arterial blood pressure and total pulmonary resistance in chronically hypoxic rats. In contrast to nifedipine, Y-27632 also markedly decreased elevated basal vascular tone in hypertensive blood-perfused lungs and isolated pulmonary arteries. Y-27632 and another Rho kinase inhibitor, HA-1077, completely reversed nitro-L-arginine-induced vasoconstriction in physiological salt solution-perfused hypertensive lungs, whereas inhibitors of myosin light chain kinase (ML-9), protein kinase C (GF-109203X), phosphatidylinositol 3-kinase (LY-294002), and tyrosine kinase (tyrphostin A23) caused only partial or no reversal of the vasoconstriction. Vasoconstrictor responses to KCl were augmented in hypertensive physiological salt solution-perfused lungs and pulmonary arteries, and the augmentation was eliminated by Y-27632. These results suggest that Rho/Rho kinase-mediated Ca2+ sensitization plays a central role in mediating sustained vasoconstriction and increased vasoreactivity in hypoxic PH.
authors.affiliation: Cardiovascular Pulmonary Research Laboratory, Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Nagaoka
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Morio
authors.forename: Nina
authors.initials: N
authors.lastname: Casanova
authors.forename: Natalie
authors.initials: N
authors.lastname: Bauer
authors.forename: Sarah
authors.initials: S
authors.lastname: Gebb
authors.forename: Ivan
authors.initials: I
authors.lastname: McMurtry
authors.forename: Masahiko
authors.initials: M
authors.lastname: Oka
mesh_terms: D000577:Amides / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D007211:Indoles / Q000494:pharmacology; D007275:Injections, Intravenous; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D011652:Pulmonary Circulation / Q000187:drug effects / Q000502:physiology*; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000494:pharmacology; D054460:rho-Associated Kinases
chemical_list: D000577:Amides; D002867:Chromones; D004791:Enzyme Inhibitors; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008301:Maleimides; D009025:Morpholines; D011725:Pyridines; D014665:Vasodilator Agents; C108830:Y 27632; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D011189:Potassium Chloride; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009543:Nifedipine; C070515:bisindolylmaleimide I