title: 5,6-EET-induced contraction of intralobar pulmonary arteries depends on the activation of Rho-kinase.
abstract: The mechanism mediating epoxyeicosatrienoic acid (EET)-induced contraction of intralobar pulmonary arteries (PA) is currently unknown. EET-induced contraction of PA has been reported to require intact endothelium and activation of the thromboxane/endoperoxide (TP) receptor. Because TP receptor occupation with the thromboxane mimetic U-46619 contracts pulmonary artery via Rho-kinase activation, we examined the hypothesis that 5,6-EET-induced contraction of intralobar rabbit pulmonary arteries is mediated by a Rho-kinase-dependent signaling pathway. In isolated rings of second-order intralobar PA (1-2 mm OD) at basal tension, 5,6-EET (0.3-10 microM) induced increases in active tension that were inhibited by Y-27632 (1 microM) and HA-1077 (10 microM), selective inhibitors of Rho-kinase activity. In PA in which smooth muscle intracellular Ca(2+) concentration ([Ca(2+)](i)) was increased with KCl (25 mM) to produce a submaximal contraction, 5,6-EET (1 microM) induced a contraction that was 7.0 +/- 1.6 times greater than without KCl. 5,6-EET (10 microM) also contracted beta-escin permeabilized PA in which [Ca(2+)](i) was clamped at a concentration resulting in a submaximal contraction. Y-27632 inhibited the 5,6-EET-induced contraction in permeabilized PA. 5,6-EET (10 microM) increased phosphorylation of myosin light chain (MLC), increasing the ratio of phosphorylated MLC/total MLC from 0.10 +/- 0.03 to 0.30 +/- 0.02. Y-27632 prevented this increase in MLC phosphorylation. These data suggest that 5,6-EET induces contraction in intralobar PA by increasing Rho-kinase activity, phosphorylating MLC, and increasing the Ca(2+) sensitivity of the contractile apparatus.
authors.affiliation: Department of Pharmacological and Physiological Science, Saint Louis University, MO 63104, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Losapio
authors.forename: Randy S
authors.initials: RS
authors.lastname: Sprague
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lonigro
authors.forename: Alan H
authors.initials: AH
authors.lastname: Stephenson
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011651:Pulmonary Artery / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D054460:rho-Associated Kinases
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D011725:Pyridines; D014662:Vasoconstrictor Agents; C108830:Y 27632; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C040776:5,6-epoxy-8,11,14-eicosatrienoic acid; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D015126:8,11,14-Eicosatrienoic Acid; D002122:Calcium Chloride