Hypoxia-induced alterations in Ca(2+) mobilization in brain microvascular endothelial cells.
To investigate the possible cellular mechanisms of the ischemia-induced impairments of cerebral microcirculation, we investigated the effects of hypoxia/reoxygenation on the intracellular Ca(2+) concentration ([Ca(2+)](i)) in bovine brain microvascular endothelial cells (BBEC). In the cells kept in normal air, ATP elicited Ca(2+) oscillations in a concentration-dependent manner. When the cells were exposed to hypoxia for 6 h and subsequent reoxygenation for 45 min, the basal level of [Ca(2+)](i) was increased from 32.4 to 63.3 nM, and ATP did not induce Ca(2+) oscillations. Hypoxia/reoxygenation also inhibited capacitative Ca(2+) entry (CCE), which was evoked by thapsigargin (Delta[Ca(2+)](i-CCE): control, 62.3 +/- 3.1 nM; hypoxia/reoxygenation, 17.0 +/- 1.8 nM). The impairments of Ca(2+) oscillations and CCE, but not basal [Ca(2+)](i), were restored by superoxide dismutase and the inhibitors of mitochondrial electron transport, rotenone and thenoyltrifluoroacetone (TTFA). By using a superoxide anion (O(2)(-))-sensitive luciferin derivative MCLA, we confirmed that the production of O(2)(-) was induced by hypoxia/reoxygenation and was prevented by rotenone and TTFA. These results indicate that hypoxia/reoxygenation generates O(2)(-) at mitochondria and impairs some Ca(2+) mobilizing properties in BBEC.
Kimura
C
C
Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
Oike
M
M
Ito
Y
Y
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002417:Cattle; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D002534:Hypoxia, Brain / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism; D008163:Luminescent Measurements; D008833:Microcirculation / Q000166:cytology / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism / Q000494:pharmacology; D012402:Rotenone / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013804:Thenoyltrifluoroacetone / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D002614:Chelating Agents; D004791:Enzyme Inhibitors; D014475:Uncoupling Agents; D012402:Rotenone; D013804:Thenoyltrifluoroacetone; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D013482:Superoxide Dismutase; D010100:Oxygen; D002118:Calcium