title: Orthovanadate-Induced Vasoconstriction of Rat Mesenteric Arteries Is Mediated by Rho Kinase-Dependent Inhibition of Myosin Light Chain Phosphatase.
abstract: Orthovanadate (OVA), a protein tyrosine phosphatase inhibitor, induces vasoconstriction in a Rho kinase-dependent manner. The aim of this study was to determine the mechanism underlying OVA-induced vasoconstriction of rat mesenteric arteries. OVA-induced constriction of mesenteric arterial rings treated with N(G)-nitro-L-arginine methyl ester (L-NAME, 0.1 mM), a nitric oxide synthase inhibitor, was significantly blocked by the Rho kinase inhibitor Y-27632 (R-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide, 10 µM), extracellular signal-regulated kinase 1 and 2 (Erk1/2) inhibitor FR180204 (5-(2-phenyl-pyrazolo[1,5-a]pyridin-3-yl)-1H-pyrazolo[3,4-c]pyridazin-3-ylamine, 10 µM), Erk1/2 kinase (MEK) inhibitor PD98059 (2'-amino-3'-methoxyflavone, 10 µM), epidermal growth factor receptor (EGFR) inhibitor AG1478 (4-(3-chloroanilino)-6,7-dimethoxyquinazoline, 10 µM), and Src inhibitor PP2 (4-amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo[3,4-d]pyrimidine, 3 µM). However, the myosin light chain kinase inhibitor ML-7 (1-(5-iodonaphthalene-1-sulfonyl)-homopiperazine, 10 µM) did not affect OVA-induced constriction. Phosphorylation of myosin phosphatase target subunit 1 (MYPT1, an index of Rho kinase activity) was abrogated by inhibitors of Src, EGFR MEK, Erk1/2, and Rho kinase. OVA-stimulated Erk1/2 phosphorylation was blocked by inhibitors of EGFR, Src, MEK, and Erk1/2 but not affected by an inhibitor of Rho kinase. OVA-induced Src phosphorylation was abrogated by an Src inhibitor but not affected by inhibitors of EGFR, MEK, Erk1/2, and Rho kinase. In addition, the metalloproteinase inhibitor TAPI-0 (N-(R)-[2-(hydroxyaminocarbonyl)methyl]-4-methylpentanoyl-L-naphthylalanyl-L-alanine amide, 10 µM) and an inhibitor of heparin/epidermal growth factor binding (CRM 197, 10 µg/mL) did not affect OVA-induced contraction of rat mesenteric arterial rings. These results suggest that OVA induces vasoconstriction in rat mesenteric arteries via Src, EGFR, MEK, and Erk1/2 activation, leading to the inactivation of myosin light chain phosphatase through phosphorylation of MYPT1.
authors.affiliation: Laboratory of Cardiovascular Pharmacology, Department of Biopharmaceutical Sciences, Kobe Gakuin University.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ito
authors.forename: Mai
authors.initials: M
authors.lastname: Matsuzaki
authors.forename: Tomoya
authors.initials: T
authors.lastname: Sasahara
authors.forename: Mariko
authors.initials: M
authors.lastname: Shin
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Yayama
mesh_terms: D000818:Animals; D066246:ErbB Receptors / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000378:metabolism; D008643:Mesentery / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000037:antagonists & inhibitors*; D010766:Phosphorylation; D000077489:Piperazine; D010879:Piperazines / Q000494:pharmacology; D054645:Protein Phosphatase 1 / Q000378:metabolism; D017208:Rats, Wistar; D015398:Signal Transduction; D014638:Vanadates / Q000494:pharmacology*; D014639:Vanadium / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*; D054460:rho-Associated Kinases / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D010879:Piperazines; D014639:Vanadium; D000077489:Piperazine; D014638:Vanadates; C483803:Egfr protein, rat; D066246:ErbB Receptors; D019061:src-Family Kinases; D054460:rho-Associated Kinases; C499850:Ppp1r12a protein, rat; D054645:Protein Phosphatase 1; D043263:Myosin-Light-Chain Phosphatase