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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, RESULTS. Meshes: Aorta, Calcium, Calcium Signaling, Cell Hypoxia, Cells, Cultured, Cyclooxygenase Inhibitors, Electron Transport, Endothelium, Vascular, Enzyme Inhibitors, Free Radical Scavengers, Humans, Hydrogen Peroxide, Hypoxia, Intracellular Fluid, NADH, NADPH Oxidoreductases, NADPH Oxidases, Nitric Oxide Synthase, Oxygen, Reactive Oxygen Species, Rotenone, Signal Transduction, Uncoupling Agents, Xanthine Oxidase.
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Does hypoxia/reoxygenation stimulate intracellular calcium oscillations in human aortic endothelial cells? Context: We have previously shown that hydrogen peroxide stimulates endothelial [Ca(2+)](i) oscillations. This study was performed to determine whether posthypoxic reoxygenation stimulates [Ca(2+)](i) 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+)](i) 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+)](i) 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+)](i) 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+)](i) 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).
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Posthypoxic reoxygenation stimulates repetitive [Ca(2+)](i) 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. Final Decision: yes