Dynamic regulation of intracellular Ca2+ concentration in aortic endothelial cells.
In non-excitable cells, a Ca2+ entry pathway is opened after the depletion of intracellular Ca2+ store sites. We have tried to estimate the sensitivity of this pathway to Ca2+ release using bovine aortic endothelial cells. Single application of a high concentration (30 microM) of ATP released almost all stored Ca2+ in Ca(2+)-free extracellular solution, whereas a low concentration of ATP (30 nM) produced a partial (57.3 +/- 3.0%) release of Ca2+. By 10 min of Ca2+ re-perfusion, the Ca2+ store site was reloaded to 97.1% of its initial filling state. When thapsigargin was applied to this cell in Mn2+ solution, Mn(2+)-induced quenching of fura-2 dye started when 19.3 +/- 5.3% of Ca2+ release, produced by 30 nM ATP, had occurred. Therefore, Ca2+ release required for Mn2+ entry was estimated as 11.1 +/- 3.0% of stored Ca2+. These results indicate that intracellular Ca2+ concentration is controlled dynamically by simultaneously occurring Ca2+ release and entry in bovine aortic endothelial cells.
Oike
M
M
Department of Pharmacology, Faculty of Medicine, Kyushu University, Japan. moike@pharmaco.med.kyushu-u.ac.jp
Ito
Y
Y
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D019284:Thapsigargin; D000251:Adenosine Triphosphatases; D002118:Calcium; D016257:Fura-2