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AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 5 1677-R1683, Copyright © 1997 by American Physiological Society
ARTICLES |
M. Wartenberg, J. Hescheler and H. Sauer
Institute for Neurophysiology, University of Cologne, Germany.
A single electrical field pulse (500 V/m) with a duration of 60 s increased tumor outgrowth over a postpulse period of 24 h. RNA staining with acridine orange showed a rise in RNA content in pulsed spheroids, indicating stimulation of cell cycle activity. The electropulse induced an intracellular Ca2+ concentration ([Ca2+]i) transient that started approximately 40 s after the onset of the electrical field. Neither the presence of extracellular Ni2+ (0.5 mM) nor the absence of extracellular Ca2+ impeded the [Ca2+]i rise. It was, however, totally blocked by thapsigargin (1 microM), indicating that the initial Ca2+ response is due to Ca2+ release from intracellular stores. The [Ca2+]i transient was paralleled by an increase in reactive oxygen species (ROS), as revealed using 2',7'-dichlorofluorescein diacetate as an indicator. The radical scavengers N-acetyl-L-cysteine (NAC)(20 mM) and dehydroascorbate (5 mM) inhibited both ROS production and the [Ca2+]i transient during electrical field treatment. The mitogenic activation was dependent on the rise in [Ca2+]i because inhibition of Ca2+ release during electrical field treatment by addition of either thapsigargin or NAC to the incubation medium abolished the observed effect. We conclude that a single, direct current electrical field pulse induces production of ROS, which in turn mediate Ca2+ release from intracellular stores and activate cell cycle activity in multicellular spheroids.
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H. Sauer, R. Stanelle, J. Hescheler, and M. Wartenberg The DC electrical-field-induced Ca2+ response and growth stimulation of multicellular tumor spheroids are mediated by ATP release and purinergic receptor stimulation J. Cell Sci., August 15, 2002; 115(16): 3265 - 3273. [Abstract] [Full Text] [PDF] |
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M. Wartenberg, F. C. Ling, M. Schallenberg, A. T. Baumer, K. Petrat, J. Hescheler, and H. Sauer Down-regulation of Intrinsic P-glycoprotein Expression in Multicellular Prostate Tumor Spheroids by Reactive Oxygen Species J. Biol. Chem., May 11, 2001; 276(20): 17420 - 17428. [Abstract] [Full Text] [PDF] |
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