title: Hydrogen peroxide-induced Ca2+ mobilization in pulmonary arterial smooth muscle cells.
abstract: Reactive oxygen species (ROS) generated from NADPH oxidases and mitochondria have been implicated as key messengers for pulmonary vasoconstriction and vascular remodeling induced by agonists and hypoxia. Since Ca(2+) mobilization is essential for vasoconstriction and cell proliferation, we sought to characterize the Ca(2+) response and to delineate the Ca(2+) pathways activated by hydrogen peroxide (H(2)O(2)) in rat intralobar pulmonary arterial smooth muscle cells (PASMCs). Exogenous application of 10 microM to 1 mM H(2)O(2) elicited concentration-dependent increase in intracellular Ca(2+) concentration in PASMCs, with an initial rise followed by a plateau or slow secondary increase. The initial phase was related to intracellular release. It was attenuated by the inositol trisphosphate (IP(3)) receptor antagonist 2-aminoethyl diphenylborate, ryanodine, or thapsigargin, but was unaffected by the removal of Ca(2+) in external solution. The secondary phase was dependent on extracellular Ca(2+) influx. It was unaffected by the voltage-gated Ca(2+) channel blocker nifedipine or the nonselective cation channel blockers SKF-96365 and La(3+), but inhibited concentration dependently by millimolar Ni(2+), and potentiated by the Na(+)/Ca(2+) exchange inhibitor KB-R 7943. H(2)O(2) did not alter the rate of Mn(2+) quenching of fura 2, suggesting store- and receptor-operated Ca(2+) channels were not involved. By contrast, H(2)O(2) elicited a sustained inward current carried by Na(+) at -70 mV, and the current was inhibited by Ni(2+). These results suggest that H(2)O(2) mobilizes intracellular Ca(2+) through multiple pathways, including the IP(3)- and ryanodine receptor-gated Ca(2+) stores, and Ni(2+)-sensitive cation channels. Activation of these Ca(2+) pathways may play important roles in ROS signaling in PASMCs.
authors: Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21224, USA.
authors: Mo-Jun
authors: MJ
authors: Lin
authors: Xiao-Ru
authors: XR
authors: Yang
authors: Yuan-Ning
authors: YN
authors: Cao
authors: James S K
authors: JS
authors: Sham
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D016257:Fura-2; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008297:Male; D008345:Manganese / Q000493:pharmacokinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011651:Pulmonary Artery / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D016877:Oxidants; D017382:Reactive Oxygen Species; D019837:Ryanodine Receptor Calcium Release Channel; D019831:Sodium-Calcium Exchanger; D008345:Manganese; D012964:Sodium; D006861:Hydrogen Peroxide; D002118:Calcium; D016257:Fura-2