Differential calcium regulation by hydrogen peroxide and superoxide in vascular smooth muscle cells from spontaneously hypertensive rats

J Cardiovasc Pharmacol. 2004 Aug;44(2):200-8. doi: 10.1097/00005344-200408000-00009.

Abstract

We investigated the role of reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2) and superoxide anion (*O2-) in the regulation of vascular smooth muscle cell (VSMC) Ca2+ concentration ([Ca2+]i) and vascular contraction and assessed whether redox-dependent Ca2+ signaling and contraction are altered in hypertension. VSMCs and mesenteric arteries from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were studied. Cells were stimulated with H2O2 (10(-4) mol/l) or LY83583 (*O2- generator, 10(-5) mol/l). [Ca2+]i and cytosolic *O2- were measured by fura-2AM and tempo-9-AC fluorescence respectively. L-type and T-type Ca2+ channels were assessed using verapamil/diltiazem and mibefradil respectively and mRNA and protein expression of these channels was assessed by real-time PCR and immunoblotting respectively. H2O2 time-dependently increased [Ca2+]i and contraction with significantly greater effects in SHR versus WKY (P < 0.001). LY83583 increased [Ca2+]i in both strains, but responses were blunted in SHR. Removal of extracellular Ca2+ abrogated [Ca2+]i responses to H2O2 and *O2-. Verapamil and diltiazem, but not mibefradil, significantly decreased H2O2 -induced [Ca2+]i responses with greater effects in SHR (P < 0.01). L-type and T-type Ca2+ channel inhibition reduced LY83583-mediated [Ca2+]i increase only in WKY cells. Both types of Ca2+ channels were expressed (mRNA and protein) in VSMCs from WKY and SHR, with greater abundance in SHR than WKY (2- to 3-fold). These results demonstrate that ROS increase vascular [Ca2+]i and contraction, primarily via extracellular Ca2+ influx. Whereas responses to H2O2 are enhanced, *O2- -mediated actions are blunted in SHR. These effects may relate to differential activation of Ca2+ channels by H2O2 and *O2-. Enhanced activation of L-type Ca2+ channels and increased Ca2+ influx by H2O2 may contribute to increased Ca2+ signaling in VSMCs from SHR.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoquinolines / metabolism
  • Aminoquinolines / pharmacology
  • Animals
  • Calcium / metabolism*
  • Calcium Channels, L-Type / chemistry
  • Calcium Channels, L-Type / drug effects
  • Calcium Channels, L-Type / genetics
  • Calcium Channels, T-Type / chemistry
  • Calcium Channels, T-Type / drug effects
  • Calcium Channels, T-Type / genetics
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Diltiazem / pharmacology
  • Dose-Response Relationship, Drug
  • Hydrogen Peroxide / metabolism*
  • Male
  • Mesenteric Arteries / cytology
  • Mesenteric Arteries / drug effects
  • Mibefradil / pharmacology
  • Muscle Contraction / drug effects
  • Muscle Contraction / physiology
  • Muscle, Smooth, Vascular / cytology*
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / metabolism
  • Rats
  • Rats, Inbred SHR
  • Rats, Inbred WKY
  • Reactive Oxygen Species / metabolism
  • Superoxides / metabolism*
  • Verapamil / pharmacology

Substances

  • Aminoquinolines
  • Calcium Channels, L-Type
  • Calcium Channels, T-Type
  • Reactive Oxygen Species
  • Superoxides
  • Mibefradil
  • 6-anilino-5,8-quinolinedione
  • Hydrogen Peroxide
  • Verapamil
  • Diltiazem
  • Calcium