title: Modulation of PGF2alpha- and hypoxia-induced contraction of rat intrapulmonary artery by p38 MAPK inhibition: a nitric oxide-dependent mechanism.
abstract: The mechanisms through which p38 mitogen-activated protein kinase (p38 MAPK) is involved in smooth muscle contraction remain largely unresolved. We examined the role of p38 MAPK in prostaglandin F(2alpha) (PGF(2alpha))-induced vasoconstriction and in hypoxic pulmonary vasoconstriction (HPV) of rat small intrapulmonary arteries (IPA). The p38 MAPK inhibitors SB-203580 and SB-202190 strongly inhibited PGF(2alpha)-induced vasoconstriction, with IC(50)s of 1.6 and 1.2 microM, whereas the inactive analog SB-202474 was approximately 30-fold less potent. Both transient and sustained phases of HPV were suppressed by SB-203580, but not by SB-202474 (both 2 microM). Western blot analysis revealed that PGF(2alpha) (20 microM) increased phosphorylation of p38 MAPK and of heat shock protein 27 (HSP27), and this was abolished by SB-203580 but not by SB-202474 (both 2 microM). Endothelial denudation or blockade of endothelial nitric oxide (NO) synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME) significantly suppressed the relaxation of PGF(2alpha)-constricted IPA by SB-203580, but not by SB-202474. Similarly, the inhibition of HPV by SB-203580 was prevented by prior treatment with L-NAME. SB-203580 (2 microM), but not SB-202474, enhanced relaxation-induced by the NO donor S-nitroso-N-acetylpenicillamine (SNAP) in endothelium-denuded IPA constricted with PGF(2alpha). In alpha-toxin-permeabilized IPA, SB-203580-induced relaxation occurred in the presence but not the absence of the NO donor sodium nitroprusside (SNP); SB-202474 was without effect even in the presence of SNP. In intact IPA, neither PGF(2alpha)- nor SNAP-mediated changes in cytosolic free Ca(2+) were affected by SB-203580. We conclude that p38 MAPK contributes to PGF(2alpha)- and hypoxia-induced constriction of rat IPA primarily by antagonizing the underlying Ca(2+)-desensitizing actions of NO.
authors.affiliation: Dept. of Asthma, Allergy & Respiratory Science, School of Medicine, King's College London, London SE1 9RT, UK.
authors.forename: Greg A
authors.initials: GA
authors.lastname: Knock
authors.forename: Anushika S
authors.initials: AS
authors.lastname: De Silva
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Snetkov
authors.forename: Richard
authors.initials: R
authors.lastname: Siow
authors.forename: Gavin D
authors.initials: GD
authors.lastname: Thomas
authors.forename: Mitsuya
authors.initials: M
authors.lastname: Shiraishi
authors.forename: Michael P
authors.initials: MP
authors.lastname: Walsh
authors.forename: Jeremy P T
authors.initials: JP
authors.lastname: Ward
authors.forename: Philip I
authors.initials: PI
authors.lastname: Aaronson
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D003251:Constriction, Pathologic / Q000139:chemically induced / Q000378:metabolism; D015237:Dinoprost / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009363:Neoplasm Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism; D009924:Organ Culture Techniques / Q000379:methods; D010120:Oxytocics / Q000008:administration & dosage*; D010766:Phosphorylation / Q000187:drug effects; D011651:Pulmonary Artery / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D010120:Oxytocics; D009569:Nitric Oxide; D015237:Dinoprost; D052250:Nitric Oxide Synthase Type III; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium