Responses of individual smooth muscle cells to sympathetic stimulation visualized within the arterial wall using confocal microscopy

我们研究了血管平滑肌细胞的交感神经控制，并获得了一些结果，使传统的观点得到重新考虑。应用共聚焦显微镜观察了大鼠尾动脉血管壁内单个平滑肌细胞内[Ca^<2+>] i随血管周围交感神经网络活动的变化。与之前的预期不同，即每个平滑肌细胞对恒定的交感神经刺激都以恒定的[Ca^2+] i升高做出反应，单个细胞显示出[Ca ^2 +] i的间歇性升高（Ca^2+振荡）。由于细胞间Ca^2+振荡的相位不同，许多细胞的平均值似乎是一个恒定的反应。因此，以前的测量未能检测到振荡。此外，由于内部储存的Ca^2+的释放，每个振荡在细胞内以大约20 μ m/s的速度作为Ca^2+波传播。因此，我们的研究结果表明，细胞内Ca^2+库在调节血管平滑肌收缩中起着重要作用。我们还清楚地表明，Ca^2+振荡在细胞功能调节中是重要的。

We studied the sympathetic control of vascular smooth muscle cells and obtained results that make the conventional view to be reconsidered. Using a confocal microscopy, we succeeded in visualizing [Ca^<2+>]_i change in individual smooth muscle cells in situ within the wall of rat tail artery in response to perivascular sympathtetic nerve network activities. Unlike the previous expectation that each smooth muscle cell respond with a constant [Ca^<2+>]_i rise to constant sympathetic stimulation, individual cells are shown to respond in intermittent rises in [Ca^<2+>]_i (Ca^<2+> oscillations). As the phases of Ca^<2+> oscillations differ from cell to cell, the average of many cells appear as if a constant response. Therefore, previous measurements failed to detect the oscillations. Furthermore, each oscillation propagated at a velocity of about 20 mum/s within the cell as Ca^<2+> wave due to release of Ca^<2+> from internal stores. Our results therefore demonstrate that intracellular Ca^<2+> stores play important roles in the regulation of vascular smooth muscle contraction. We have also shown clearly that Ca^<2+> oscillations are important in the regulation of cell functions.