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首页> 外文期刊>American Journal of Physiology >Sphingosine-1-phosphate activates BKCa channels independently of G protein-coupled receptor in human endothelial cells.
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Sphingosine-1-phosphate activates BKCa channels independently of G protein-coupled receptor in human endothelial cells.

机译：1-磷酸鞘氨醇可独立于人内皮细胞中的G蛋白偶联受体激活BKCa通道。

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摘要

The effect of sphingosine-1-phosphate (S1P) on large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels was examined in primary cultured human umbilical vein endothelial cells by measuring intracellular Ca(2+) concentration ([Ca(2+)](i)), whole cell membrane currents, and single-channel activity. In nystatin-perforated current-clamped cells, S1P hyperpolarized the membrane and simultaneously increased [Ca(2+)](i). [Ca(2+)](i) and membrane potentials were strongly correlated. In whole cell clamped cells, BK(Ca) currents were activated by increasing [Ca(2+)](i) via cell dialysis with pipette solution, and the activated BK(Ca) currents were further enhanced by S1P. When [Ca(2+)](i) was buffered at 1 microM, 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 Ca(2+) 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) (GDPbetaS; 1 mM) using a patch pipette, GDPbetaS application or pretreatment of cells with pertussis toxin (100 ng/ml) for 15 h did not affect S1P-induced BK(Ca) current and channel activation. These results suggest that S1P enhances BK(Ca) channel activity by increasing Ca(2+) sensitivity. This channel activation hyperpolarizes the membrane and thereby increases Ca(2+) influx through Ca(2+) entry channels. Inasmuch as S1P activates BK(Ca) channels via a mechanism independent of G protein-coupled receptors, S1P may be a component of the intracellular second messenger that is involved in Ca(2+) mobilization in human endothelial cells.
机译：鞘氨醇-1-磷酸（S1P）对大电导Ca（2+）激活的K（+）（BK（Ca））通道的影响通过测量细胞内Ca（2+）在原代培养的人脐静脉内皮细胞中进行了检查）浓度（[Ca（2 +）]（i）），全细胞膜电流和单通道活性。在制霉菌素穿孔的电流钳细胞中，S1P使膜超极化，并同时增加[Ca（2 +）]（i）。 [Ca（2 +）]（i）与膜电位高度相关。在全细胞钳制的细胞中，通过用移液器通过细胞透析增加[Ca（2 +）]（i）激活BK（Ca）电流，并且通过S1P进一步增强了激活的BK（Ca）电流。当[Ca（2 +）]（i）缓冲至1 microM时，引起半数最大激活所需的S1P浓度为403 +/- 13 nM。在由内而外的贴片中，当浴溶液中包含S1P时，S1P以可逆的方式增强BK（Ca）通道活性，并向左移浴溶液中Ca（2+）浓度与平均打开概率之间的关系。在全细胞钳制的细胞或内装有鸟苷5'-O-（2-硫代二磷酸）（GDPbetaS; 1 mM）的内向外补丁中，GDPbetaS应用或用百日咳毒素（100 ng / ml）预处理细胞15小时不影响S1P诱导的BK（Ca）电流和通道激活。这些结果表明，S1P通过增加Ca（2+）敏感性来增强BK（Ca）通道活性。此通道激活使膜超极化，从而增加通过Ca（2+）进入通道的Ca（2+）流入量。由于S1P通过独立于G蛋白偶联受体的机制激活BK（Ca）通道，因此S1P可能是参与人内皮细胞Ca（2+）动员的细胞内第二信使的组成部分。

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