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 fura2AM 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 [Ca 2+]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 Ca 2+ 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 H2O 2 are enhanced, .O2--mediated actions are blunted in SHR. These effects may relate to differential activation of Ca2+ channels by H2O2 and .O 2-. Enhanced activation of L-type Ca2+ channels and increased Ca2+ influx by H2O2 may contribute to increased Ca2+ signaling in VSMCs from SHR.
Differential calcium regulation by hydrogen peroxide and superoxide in vascular smooth muscle cells from spontaneously hypertensive rats / Fatiha, Tabet; Savoia, Carmine; Ernesto L., Schiffrin; Rhian M., Touyz. - In: JOURNAL OF CARDIOVASCULAR PHARMACOLOGY. - ISSN 0160-2446. - 44:2(2004), pp. 200-208. [10.1097/00005344-200408000-00009]
Differential calcium regulation by hydrogen peroxide and superoxide in vascular smooth muscle cells from spontaneously hypertensive rats
SAVOIA, Carmine;
2004
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 fura2AM 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 [Ca 2+]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 Ca 2+ 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 H2O 2 are enhanced, .O2--mediated actions are blunted in SHR. These effects may relate to differential activation of Ca2+ channels by H2O2 and .O 2-. Enhanced activation of L-type Ca2+ channels and increased Ca2+ influx by H2O2 may contribute to increased Ca2+ signaling in VSMCs from SHR.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
