Cytosolic Ca 2+ movements of endothelial cells exposed to reactive oxygen intermediates: Role of hydroxyl radical‐mediated redox alteration of cell‐membrane Ca 2+ channels
The mode of action of reactive oxygen intermediates in cysosolic Ca 2+ movements of cultured porcine aortic endothelial cells exposed to xanthine/xanthine oxidase (X/XO) was investigated. Cytosolic Ca 2+ movements provoked by X/XO consisted of an initial Ca 2+ release from thapsigargin‐sensitive int...
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| Published in | British journal of pharmacology Vol. 126; no. 6; pp. 1462 - 1470 |
|---|---|
| Main Authors | , , |
| Format | Journal Article |
| Language | English |
| Published |
29.01.2009
|
| Online Access | Get full text |
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| Summary: | The mode of action of reactive oxygen intermediates in cysosolic Ca
2+
movements of cultured porcine aortic endothelial cells exposed to xanthine/xanthine oxidase (X/XO) was investigated.
Cytosolic Ca
2+
movements provoked by X/XO consisted of an initial Ca
2+
release from thapsigargin‐sensitive intracellular Ca
2+
stores and a sustained Ca
2+
influx through cell‐membrane Ca
2+
channels. The Ca
2+
movements from both sources were inhibited by catalase, cell‐membrane permeable iron chelators (o‐phenanthroline and deferoxamine), a
•
OH scavenger (5,5‐dimethyl‐1‐pyrroline‐N‐oxide), or an anion channel blocker (disodium 4, 4′‐diisothiocyano‐2, 2′‐stilbenedisulphonic acid), suggesting that
•
O
2
−
influx through anion channels was responsible for the Ca
2+
movements, in which
•
OH generation catalyzed by intracellular transition metals (i.e., Haber‐Weiss cycle) was involved.
After an initial Ca
2+
elevation provoked by X/XO, cytosolic Ca
2+
concentration decreased to a level higher than basal levels. Removal of X/XO slightly enhanced the Ca
2+
decrease. Extracellular addition of sulphydryl (SH)‐reducing agents, dithiothreitol or glutathione, after the removal of X/XO accelerated the decrement. A Ca
2+
channel blocker, Ni
2+
, abolished the sustained increase in Ca
2+
, suggesting that Ca
2+
influx through cell‐membrane Ca
2+
channels was extracellularly regulated by the redox state of SH‐groups.
The X/XO‐provoked change in cellular respiration was inhibited by Ni
2+
or dithiothreitol as well as inhibitors of Haber‐Weiss cycle, suggesting that Ca
2+
influx was responsible for
•
OH‐mediated cytotoxicity. We concluded that intracellular
•
OH generation was involved in the Ca
2+
movements in endothelial cells exposed to X/XO. Cytosolic Ca
2+
elevation was partly responsible for the oxidants‐mediated cytotoxicity.
British Journal of Pharmacology
(1999)
126
, 1462–1470; doi:
10.1038/sj.bjp.0702438 |
|---|---|
| ISSN: | 0007-1188 1476-5381 |
| DOI: | 10.1038/sj.bjp.0702438 |