Hydrogen peroxide induces intracellular calcium oscillations in human aortic endothelial cells

• Published in: Circulation (New York, N.Y.) N.Y.), 1998-01, Vol.97 (3), p.268-275
• Main Authors: HU, Q, CORDA, S, ZWEIER, J. L, CAPOGROSSI, M. C, ZIEGELSTEIN, R. C
• Format: Article
• Language: English
• Subjects: Aorta - cytology; Aorta - drug effects; Aorta - metabolism; Biological and medical sciences; Blood vessels and receptors; Buffers; Calcium - physiology; Cells, Cultured; Cytosol - physiology; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Extracellular Space - physiology; Fundamental and applied biological sciences. Psychology; Histamine - pharmacology; Humans; Hydrogen Peroxide - pharmacology; Oxidants - pharmacology; Signal Transduction - drug effects; Signal Transduction - physiology; Vertebrates: cardiovascular system
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.97.3.268

Because the vascular endothelium is exposed to oxidant stress resulting from ischemia/reperfusion and from the products of polymorphonuclear leukocytes or monocytes, studies were performed to examine the effect of hydrogen peroxide (1 micromol/L to 10 mmol/L) on endothelial Ca2+ signaling. At low concentrations (1 to 10 micromol/L), hydrogen peroxide did not affect intracellular Ca2+ concentration in subconfluent, indo 1-loaded human aortic endothelial monolayers. At a concentration of 100 micromol/L hydrogen peroxide, intracellular free Ca2+ gradually increased from 125.3+/-6.8 to 286.3+/-19.9 nmol/L over 4.2+/-0.9 minutes before repetitive Ca2+ oscillations were observed, consisting of an initial large, transient spike of approximately 1 micromol/L followed by several spikes of decreasing amplitudes at a frequency of 0.7+/-0.1 min-1 over 12.0+/-1.1 minutes. After these oscillations, intracellular Ca2+ reached a plateau of 543.4+/-64.0 nmol/L, which was maintained above baseline levels for >5 minutes and then partially reversible on washout of hydrogen peroxide in most monolayers. Intracellular Ca2+ oscillations were typically observed when monolayers were exposed to 100 to 500 micromol/L hydrogen peroxide. Higher concentrations of hydrogen peroxide (1 and 10 mmol/L) increased intracellular Ca2+ but only rarely (2 of 6 monolayers at 1 mmol/L) or never (at 10 mmol/L) stimulated intracellular Ca2+ oscillations. Removal of Ca2+ from the buffer either before hydrogen peroxide stimulation or during an established response did not block intracellular Ca2+ oscillations in response to 100 micromol/L hydrogen peroxide, but prior depletion of an intracellular Ca2+ store with either caffeine, histamine, or thapsigargin abolished Ca2+ oscillations. Hydrogen peroxide induces concentration-dependent intracellular Ca2+ oscillations in human endothelial cells, which results from release of an endoplasmic reticulum Ca2+ store. Because oxidant production appears to occur in the micromolar range in the postischemic/anoxic endothelium and is associated with impaired endothelium-dependent relaxation, the effects of micromolar concentrations of hydrogen peroxide on endothelial Ca2+ signaling described in the present study may be important in the pathogenesis of postischemic endothelial dysfunction.