title: Hydrogen peroxide induces contraction and raises [Ca2+]i in canine cerebral arterial smooth muscle: participation of cellular signaling pathways.
abstract: The effects of hydrogen peroxide (H2O2) on isolated canine basilar arteries, and single smooth muscle cells isolated from these arteries, were investigated in the present study. Exposure of isolated endothelium-intact and denuded arterial rings to H2O2, at concentrations of 2.2x10(-5) M to 4.4x10(-3) M, produced concentration-dependent contractile responses. Removal of the endothelium attenuated, but did not eliminate the contractions. H2O2-induced contractions were inhibited, to different degrees, by preincubation of the vessels with low concentrations of staurosporine or bisindolylmaleimide I HCl [antagonists of protein kinase C (PKC)], Gö6976 (a PKCalpha and PKCbeta1 selective antagonist), genistein (an antagonist of protein tyrosine kinase), PD-98059 (an antagonist of mitogen-activated protein kinase), wortmannin [an antagonist of phosphatidylinositol 3 (PI3)-kinases], and LY-294002 (an antagonist of PI3-kinases). These agents were also found to relax arteries precontracted by H2O2. Removal of extracellular Ca2+ or pretreatment of the vessels with 5.0 microM verapamil markedly attenuated the contractions. Complete inhibition of the contractile response was obtained after buffering intracellular Ca2+ with BAPTA-AM. A variety of specific pharmacological antagonists of several known vasoconstrictors neither inhibited nor attenuated the H2O2-induced contractions. Exposure of smooth muscle cells to H2O2 (4.4x10(-6) M to 4.4x10(-4) M) significantly raised intracellular Ca2+ ([Ca2+]i) within 20 s. This was abolished in the absence of extracellular Ca2+ or after application of 5.0 microM verapamil. Pretreatment of the cells with low concentrations of staurosporine, bisindolylmaleimide I, Gö6976, genistein, PD-98059, wortmannin, and LY-294002 markedly suppressed the H2O2-mediated [Ca2+]i elevation. The present findings suggest that hydrogen peroxide, in vitro, produces endothelium-dependent and independent contractions of canine basilar arteries, which are clearly Ca2+-dependent and are not associated with release of endogenous vasoconstrictors. Several intracellular signal transduction systems, such as PKC (both Ca2+-dependent and Ca2+-independent), protein tyrosine phosphorylation, IP3, mitogen-activated protein kinase and PI3 kinase appear to play a role in the H2O2-induced contractions in cerebral arterial muscle.
authors.affiliation: Department of Physiology, State University of New York, Health Science Center at Brooklyn, 11203, USA.
authors.forename: Z W
authors.initials: ZW
authors.lastname: Yang
authors.forename: T
authors.initials: T
authors.lastname: Zheng
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Zhang
authors.forename: B T
authors.initials: BT
authors.lastname: Altura
authors.forename: B M
authors.initials: BM
authors.lastname: Altura
mesh_terms: D000818:Animals; D001488:Basilar Artery; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D002536:Cerebral Arteries / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D002614:Chelating Agents / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects; D020301:Vasospasm, Intracranial / Q000139:chemically induced* / Q000503:physiopathology
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D000081082:Phosphoinositide-3 Kinase Inhibitors; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium