title: Involvement of gap junctions between smooth muscle cells in sustained hypoxic pulmonary vasoconstriction development: a potential role for 15-HETE and 20-HETE.
abstract: In response to hypoxia, the pulmonary artery normally constricts to maintain optimal ventilation-perfusion matching in the lung, but chronic hypoxia leads to the development of pulmonary hypertension. The mechanisms of sustained hypoxic pulmonary vasoconstriction (HPV) remain unclear. The aim of this study was to determine the role of gap junctions (GJs) between smooth muscle cells (SMCs) in the sustained HPV development and involvement of arachidonic acid (AA) metabolites in GJ-mediated signaling. Vascular tone was measured in bovine intrapulmonary arteries (BIPAs) using isometric force measurement technique. Expression of contractile proteins was determined by Western blot. AA metabolites in the bath fluid were analyzed by mass spectrometry. Prolonged hypoxia elicited endothelium-independent sustained HPV in BIPAs. Inhibition of GJs by 18β-glycyrrhetinic acid (18β-GA) and heptanol, nonspecific blockers, and Gap-27, a specific blocker, decreased HPV in deendothelized BIPAs. The sustained HPV was not dependent on Ca(2+) entry but decreased by removal of Ca(2+) and by Rho-kinase inhibition with Y-27632. Furthermore, inhibition of GJs decreased smooth muscle myosin heavy chain (SM-MHC) expression and myosin light chain phosphorylation in BIPAs. Interestingly, inhibition of 15- and 20-hydroxyeicosatetraenoic acid (HETE) synthesis decreased HPV in deendothelized BIPAs. 15-HETE- and 20-HETE-stimulated constriction of BIPAs was inhibited by 18β-GA and Gap-27. Application of 15-HETE and 20-HETE to BIPAs increased SM-MHC expression, which was also suppressed by 18β-GA and by inhibitors of lipoxygenase and cytochrome P450 monooxygenases. More interestingly, 15,20-dihydroxyeicosatetraenoic acid and 20-OH-prostaglandin E2, novel derivatives of 20-HETE, were detected in tissue bath fluid and synthesis of these derivatives was almost completely abolished by 18β-GA. Taken together, our novel findings show that GJs between SMCs are involved in the sustained HPV in BIPAs, and 15-HETE and 20-HETE, through GJs, appear to mediate SM-MHC expression and contribute to the sustained HPV development.
authors.affiliation: Department of Experimental Therapeutics, Institute of Pharmacology and Toxicology of NAMS of Ukraine, Kiev, Ukraine; Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Igor V
authors.initials: IV
authors.lastname: Kizub
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Anand
authors.initials: A
authors.lastname: Lakhkar
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Vidhi
authors.initials: V
authors.lastname: Dhagia
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Sachindra R
authors.initials: SR
authors.lastname: Joshi
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Houli
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Physiology, New York Medical College, Valhalla, New York;
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolin
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas; and.
authors.forename: John R
authors.initials: JR
authors.lastname: Falck
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas; and.
authors.forename: Sreenivasulu Reddy
authors.initials: SR
authors.lastname: Koduru
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas; and.
authors.forename: Ramu
authors.initials: R
authors.lastname: Errabelli
authors.affiliation: Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Jacobs
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York;
authors.forename: Michal L
authors.initials: ML
authors.lastname: Schwartzman
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York; s_gupte@nymc.edu sachin_gupte@yahoo.com.
authors.forename: Sachin A
authors.initials: SA
authors.lastname: Gupte
mesh_terms: D000818:Animals; D002417:Cattle; D015687:Cell Hypoxia; D002478:Cells, Cultured; D042783:Endothelial Cells; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology; D014661:Vasoconstriction
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D018995:Myosin Heavy Chains
keywords: 15,20-dihydroxyeicosatetraenoic acid; 15-hydroxyeicosatetraenoic acid; 20-OH-prostaglandin E2; 20-hydroxyeicosatetraenoic acid; arachidonic acid metabolites; bovine pulmonary artery; gap junctions; hypoxic pulmonary vasoconstriction