Hu Q, Ziegelstein R C
Department of Medicine, Division of Cardiology, Johns Hopkins Bayview Medical Center, Johns Hopkins University School of Medicine, Baltimore, MD 21224-2780, USA.
Circulation. 2000 Nov 14;102(20):2541-7. doi: 10.1161/01.cir.102.20.2541.
We have previously shown that hydrogen peroxide stimulates endothelial Ca(2+) oscillations. This study was performed to determine whether posthypoxic reoxygenation stimulates Ca(2+) oscillations in vascular endothelial cells.
Hypoxia (glucose-free 95% N(2)/5% CO(2) bicarbonate buffer for 60 minutes) stimulated an increase in Ca(2+) from 111.9+/-7. 9 to 161.7+/-17.7 nmol/L (n=12, P:<0.01) in indo 1-loaded human aortic endothelial cells. On reoxygenation (glucose-containing 95% air/5% CO(2) bicarbonate buffer), 13 of 16 cells responded with repetitive Ca(2+) oscillations with an average amplitude of 570. 6+/-59.3 nmol/L, occurring at a mean interval of 0.28+/-0.04/min and persisting for >/=60 minutes. Ca(2+) oscillations were still observed in 4 of 7 cells studied in Ca(2+)-free buffer but did not occur when the intracellular Ca(2+) store was first depleted during hypoxia by either 1 micromol/L thapsigargin or by 10 mmol/L caffeine (n=6 for each). Reoxygenation-induced Ca(2+) oscillations were abolished by 10 micromol/L diphenyleneiodonium, an inhibitor of NAD(P)H oxidase (n=7), and by polyethylene glycol (PEG)-catalase (5000 U/mL, n=4) but were not prevented by inhibitors of xanthine oxidase (n=5), cyclooxygenase (n=4), nitric oxide synthase (n=5), the mitochondrial electron transport chain (n=4), or by PEG-superoxide dismutase (n=5).
Posthypoxic reoxygenation stimulates repetitive Ca(2+) oscillations that are dependent on Ca(2+) release from an intracellular pool and require extracellular Ca(2+) to be maintained. These oscillations may be initiated by NAD(P)H oxidase-derived hydrogen peroxide and may play a role in signal transduction during ischemia/reperfusion in vivo.
我们之前已经表明过氧化氢可刺激内皮细胞内钙离子（Ca(2+)）振荡。本研究旨在确定缺氧后复氧是否会刺激血管内皮细胞中的Ca(2+)振荡。
缺氧（在无糖的95%氮气/5%二氧化碳碳酸氢盐缓冲液中处理60分钟）使负载indo 1的人主动脉内皮细胞内的Ca(2+)从111.9±7.9增加到161.7±17.7 nmol/L（n = 12，P < 0.01）。复氧（在含葡萄糖的95%空气/5%二氧化碳碳酸氢盐缓冲液中）时，16个细胞中有13个出现重复性的Ca(2+)振荡，平均振幅为570.6±59.3 nmol/L，平均间隔为0.28±0.04/分钟，持续≥60分钟。在无钙缓冲液中研究的7个细胞中有4个仍观察到Ca(2+)振荡，但当在缺氧期间通过1 μmol/L毒胡萝卜素或10 mmol/L咖啡因首先耗尽细胞内钙库时则未出现Ca(2+)振荡（每种情况n = 6）。复氧诱导的Ca(2+)振荡被10 μmol/L二苯碘鎓（NAD(P)H氧化酶抑制剂，n = 7）和聚乙二醇（PEG）-过氧化氢酶（5000 U/mL，n = 4）消除，但未被黄嘌呤氧化酶抑制剂（n = 5）、环氧合酶抑制剂（n = 4）、一氧化氮合酶抑制剂（n = 5）、线粒体电子传递链抑制剂（n = 4）或PEG-超氧化物歧化酶（n = 5）阻止。
缺氧后复氧刺激重复性的Ca(2+)振荡，其依赖于细胞内钙库释放钙离子并需要细胞外钙离子来维持。这些振荡可能由NAD(P)H氧化酶衍生的过氧化氢引发，并且可能在体内缺血/再灌注期间的信号转导中起作用。
