Hypoxia-induced alterations in Ca(2+) mobilization in brain microvascular endothelial cells.

Abstract

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.

• Authors: C Kimura, M Oike, Y Ito
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 279 Issue 5 Pg. H2310-8 (Nov 2000) ISSN: 0363-6135 [Print] United States
• PMID: 11045967 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Chelating Agents
• Enzyme Inhibitors
• Uncoupling Agents
• Rotenone
• Thenoyltrifluoroacetone
• Thapsigargin
• Adenosine Triphosphate
• Superoxide Dismutase
• Oxygen
• Calcium

Topics

• Adenosine Triphosphate (metabolism, pharmacology)
• Animals
• Brain (metabolism)
• Calcium (metabolism)
• Calcium Signaling (drug effects)
• Cattle
• Cells, Cultured
• Chelating Agents (pharmacology)
• Dose-Response Relationship, Drug
• Endothelium, Vascular (cytology, metabolism)
• Enzyme Inhibitors (pharmacology)
• Hypoxia, Brain (metabolism)
• Intracellular Fluid (metabolism)
• Luminescent Measurements
• Microcirculation (cytology, metabolism)
• Oxygen (metabolism, pharmacology)
• Rotenone (pharmacology)
• Superoxide Dismutase (metabolism, pharmacology)
• Thapsigargin (pharmacology)
• Thenoyltrifluoroacetone (pharmacology)
• Uncoupling Agents (pharmacology)