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Sphingosine-1-phosphate activates BKCa channels independently of G protein-coupled receptor in human endothelial cells
- Sphingosine-1-phosphate activates BKCa channels independently of G protein-coupled receptor in human endothelial cells
- Moon Y.K.; Guo H.L.; Ji A.K.; Young J.K.; Oh S.; Suh H.S.
- Ewha Authors
- 김영주; 서석효; 오세관
- SCOPUS Author ID
- 김영주; 서석효; 오세관
- Issue Date
- Journal Title
- American Journal of Physiology - Cell Physiology
- American Journal of Physiology - Cell Physiology vol. 290, no. 4, pp. C1000 - C1008
- SCI; SCIE; SCOPUS
- Document Type
- The effect of sphingosine-1-phosphate (S1P) on large-conductance Ca 2+-activated K+ (BKCa) channels was examined in primary cultured human umbilical vein endothelial cells by measuring intracellular Ca2+ concentration ([Ca2+]i), whole cell membrane currents, and single-channel activity. In nystatin-perforated current-clamped cells, S1P hyperpolarized the membrane and simultaneously increased [Ca2+]i. [Ca2+] i and membrane potentials were strongly correlated. In whole cell clamped cells, BKCa currents were activated by increasing [Ca 2+]i via cell dialysis with pipette solution, and the activated BKCa currents were further enhanced by S1P. When [Ca 2+]i was buffered at 1 μM, the S1P concentration required to evoke half-maximal activation was 403 ± 13 nM. In inside-out patches, when S1P was included in the bath solution, S1P enhanced BK Ca channel activity in a reversible manner and shifted the relationship between Ca2+ concentration in the bath solution and the mean open probability to the left. In whole cell clamped cells or inside-out patches loaded with guanosine 5′-O-(2-thiodiphosphate) (GDPβS; 1 mM) using a patch pipette, GDPβS application or pretreatment of cells with pertussis toxin (100 ng/ml) for 15 h did not affect S1P-induced BKCa current and channel activation. These results suggest that S1P enhances BK Ca channel activity by increasing Ca2+ sensitivity. This channel activation hyperpolarizes the membrane and thereby increases Ca 2+ influx through Ca2+ entry channels. Inasmuch as S1P activates BKCa channels via a mechanism independent of G protein-coupled receptors, S1P may be a component of the intracellular second messenger that is involved in Ca2+ mobilization in human endothelial cells. Copyright © 2006 the American Physiological Society.
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