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Hydrogen peroxide constricts rat arteries by activating Na+-permeable and Ca2+-permeable cation channels
Authors:Hyun Ji Park  Kyung Chul Shin  Soon-Kyu Yoou  Myeongsin Kang  Jae Gon Kim  Dong Jun Sung
Institution:1. Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju, Republic of Korea;2. Department of Emergency Medical Services, Eulji University, Seongnam, Republic of Korea;3. Division of Sport and Health Science, College of Biomedical and Health Science, Konkuk University, Chungju, Republic of Korea
Abstract:Oxidative stress is associated with many cardiovascular diseases, such as hypertension and arteriosclerosis. Oxidative stress reportedly activates the L-type voltage-gated calcium channel (VDCCL) and elevates Ca2+]i in many cells. However, how oxidative stress activates VDCCL under clinical setting and the consequence for arteries are unclear. Here, we examined the hypothesis that hydrogen peroxide (H2O2) regulates membrane potential (Em) by altering Na+ influx through cation channels, which consequently activates VDCCL to induce vasoconstriction in rat mesenteric arteries. To measure the tone of the endothelium-denuded arteries, a conventional isometric organ chamber was used. Membrane currents and Em were recorded by the patch-clamp technique. Ca2+]i and Na+]i were measured with microfluorometry using Fura2-AM and SBFI-AM, respectively. We found that H2O2 (10 and 100 µM) increased arterial contraction, and nifedipine blocked the effects of H2O2 on isometric contraction. H2O2 increased Ca2+]i as well as Na+]i, and depolarised Em. Gd3+ (1 µM) blocked all these H2O2-induced effects including Em depolarisation and increases in Ca2+]i and Na+]i. Although both nifedipine (30?nM) and low Na+ bath solution completely prevented the H2O2-induced increase in Na+], they only partly inhibited the H2O2-induced effects on Ca2+]i and Em. Taken together, the results suggested that H2O2 constricts rat arteries by causing Em depolarisation and VDCCL activation through activating Gd3+-and nifedipine-sensitive, Na+-permeable channels as well as Gd3+-sensitive Ca2+-permeable cation channels. We suggest that unidentified Na+-permeable cation channels as well as Ca2+-permeable cation channels may function as important mediators for oxidative stress-induced vascular dysfunction.
Keywords:Hydrogen peroxide  L-type voltage-dependent Ca2+ channel  membrane potential  non-selective cation channel  oxidative stress  vasoconstriction
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