Pulsatile and steady flow-induced calcium oscillations in single cultured endothelial cells
Pulsatile and steady flow-induced calcium oscillations in single cultured endothelial cells
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DOI：
10.1159/000159164
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发表时间：
1996-09-01
影响因子：
1.7
通讯作者：
Nerem, RM
中科院分区：
文献类型：
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作者：
Helmlinger, G;Berk, BC;Nerem, RM
流体施加的剪切应力对培养的内皮细胞（ECs）的胞内钙浓度（[Ca ~（2+）]（i））的影响仍不完全清楚。在本研究中，我们测量[Ca 2 +]（i）在单个牛主动脉EC，使用荧光比率图像分析。分析了几种流动模式的影响：稳定剪切应力（5-70 dyn/cm（2）），1 Hz脉动剪切应力（非反向40 +/- 30 dyn/cm（2），反向20 +/- 40 dyn/cm（2），或纯振荡0 +/- 20 dyn/cm（2）），或改变剪切应力水平。在所有流动条件下，单细胞分析显示流动诱导的异步[Ca 2 +]（i）振荡，其在单层上随机发生，并且在对应于单层响应的平均[Ca 2 +]（i）信号中未观察到。单细胞[Ca 2 +]（i）振荡的数量和相应的振荡频率随着与稳定流相关的剪切应力的增加而增加：5 dyn/cm（2）时为0.06 +/- 0.02 min（-1），20 dyn/cm（2）时为0.19 +/- 0.03 min（-1），70 dyn/cm（2）时为0.28 +/- 0.02 min（-1）（平均值+/- SD）。还有：对于任何类型的脉动流，（40 +/- 20 dyn/cm（2）时为0.53 +/- 0.07 min（-1），20 +/- 40 dyn/cm（2）时为0.54 +/- 0.08 min（-1），0 +/- 20 dyn/cm（2）时为0.39 +/- 0.07 min（-1）），与任何水平的稳定流相比。最引人注目的发现是，纯粹的振荡流诱导许多单细胞[Ca 2 +]（i）振荡，但单层的平均[Ca 2 +]（i）响应没有变化。此外，EC单层从低到高（或从高到低）的稳定流切换一致地显示出单细胞[Ca 2 +]（i）振荡的数量增加（或减少）。这些实验表明，内皮细胞通过改变单细胞[Ca ~（2+）]（i）振荡活性来响应不同的流动条件，这可能在血管生理学的内皮依赖性控制中具有重要意义，例如血管活性物质的释放。
The Influence of flow-imposed shear stress on the intracellular calcium concentration ([Ca2+](i)) of cultured endothelial cells (ECs) remains incompletely understood. In the present study, we measured [Ca2+](i) in single bovine aortic ECs, using fluorescence ratiometric image analysis. The effects of several flow patterns were analysed: steady shear stress (5-70 dyn/cm(2)), 1-Hz pulsatile shear stress (nonreversing 40 +/- 30 dyn/cm(2), reversing 20 +/- 40 dyn/cm(2), or purely oscillatory 0 +/- 20 dyn/cm(2)), or changing shear stress levels. Under all flow conditions, single-cell analyses revealed flow-induced asynchronous [Ca2+](i) oscillations, which occurred randomly over the monolayer and which were not seen in the average [Ca2+](i) signal corresponding to the monolayer response. The number of single-cell [Ca2+](i) oscillations and the corresponding oscillation frequency rose as the shear stress associated with the steady flow increased: 0.06 +/- 0.02 min(-1) at 5 dyn/cm(2), 0.19 +/- 0.03 min(-1) at 20 dyn/cm(2), and 0.28 +/- 0.02 min(-1) at 70 dyn/cm(2) (means +/- SD). Also: the number of oscillations was greater for any type of pulsatile flow (0.53 +/- 0.07 min(-1) at 40 +/- 20 dyn/cm(2), 0.54 +/- 0.08 min(-1) at 20 +/- 40 dyn/cm(2), and 0.39 +/- 0.07 min(-1) at 0 +/- 20 dyn/cm(2)), as compared to any level of steady flow. The most dramatic finding was that purely oscillatory flow induced numerous single-cell [Ca2+](i) oscillations, yet the average [Ca2+](i) response for the monolayer did not change. Furthermore, an EC monolayer switched from low to high (or from high to low) steady flow consistently showed an increase (or a decrease) in the number of single-cell [Ca2+](i) oscillations. These experiments show that ECs respond to different flow conditions by varying single-cell [Ca2+](i) oscillatory activity, This may have important implications in the endothelium-dependent control of vascular physiology, such as the release of vasoactive substances.