title: Effects of omega-hydroxylase product on distal human pulmonary arteries.
abstract: The aim of the present study was to provide a mechanistic insight into how 20-hydroxyeicosatetraenoic acid (20-HETE) relaxes distal human pulmonary arteries (HPAs). This compound is produced by omega-hydroxylase from free arachidonic acid. Tension measurements, performed on either fresh or 1 day-cultured pulmonary arteries, revealed that the contractile responses to 1 microM 5-hydroxytryptamine were largely relaxed by 20-HETE in a concentration-dependent manner (0.01-10 microM). Iberiotoxin pretreatments (10 nM) partially decreased 20-HETE-induced relaxations. However, 10 microM indomethacin and 3 microM SC-560 pretreatments significantly reduced the relaxations to 20-HETE in these tissues. The relaxing responses induced by the eicosanoid were likely related to a reduced Ca2+ sensitivity of the myofilaments since free Ca2+ concentration ([Ca2+])-response curves performed on beta-escin-permeabilized cultured explants were shifted toward higher [Ca2+]. 20-HETE also abolished the tonic responses induced by phorbol-ester-dibutyrate (a PKC-sensitizing agent). Western blot analyses, using two specific primary antibodies against the PKC-potentiated inhibitory protein CPI-17 and its PKC-dependent phosphorylated isoform pCPI-17, confirmed that 20-HETE interferes with this intracellular process. We also investigated the effect of 20-HETE on the activation of Rho-kinase pathway-induced Ca2+ sensitivity. The data demonstrated that 20-HETE decreased U-46619-induced Ca2+ sensitivity on arteries. Hence, this observation was correlated with an increased staining of p116(Rip), a RhoA-binding protein. Together, these results strongly suggest that the 20-hydroxyarachidonic acid derivative is a potent modulator of tone in HPAs in vitro.
authors.affiliation: Le Bilarium, Department of Physiology and Biophysics, Université de Sherbrooke, 3001 12th Ave. N, Sherbrooke, J1H 5N4, QC, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Morin
authors.forename: Christelle
authors.initials: C
authors.lastname: Guibert
authors.forename: Marco
authors.initials: M
authors.lastname: Sirois
authors.forename: Vincent
authors.initials: V
authors.lastname: Echave
authors.forename: Marcio M
authors.initials: MM
authors.lastname: Gomes
authors.forename: Eric
authors.initials: E
authors.lastname: Rousseau
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics; D015153:Blotting, Western; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D042926:Cytochrome P-450 CYP4A / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000502:physiology; D004928:Escin / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D007537:Isometric Contraction / Q000502:physiology; D009124:Muscle Proteins; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D010455:Peptides / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011651:Pulmonary Artery / Q000201:enzymology*; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016861:Cyclooxygenase Inhibitors; D006893:Hydroxyeicosatetraenoic Acids; D047908:Intracellular Signaling Peptides and Proteins; C498552:MPRIP protein, human; D009124:Muscle Proteins; C107507:PPP1R14A protein, human; D010455:Peptides; D024681:Potassium Channels, Calcium-Activated; D004928:Escin; C064719:iberiotoxin; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D042926:Cytochrome P-450 CYP4A; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases