Analysis of calcium oscillations in vascular smooth muscle cells

我们利用冷却的CCD摄像机或激光共聚焦扫描显微镜，对完整动脉组织内血管平滑肌细胞内钙离子浓度进行了数字成像。将钙指示剂负载动脉组织置于倒置显微镜台上的实验室中，用场电刺激或溶液交换的方法刺激。我们可以观察到单个平滑肌细胞内钙离子浓度的变化，并证实了我们以前的结果，当交感神经递质去甲肾上腺素刺激动脉组织时，细胞内钙离子浓度的变化是以钙振荡和波动的形式发生的。目前的实验系统比我们以前的测量系统具有更大的动态范围。我们研究了二氢吡啶钙通道拮抗剂对钙离子振荡的影响。当尼卡地平的浓度足以抑制高钾引起的血管平滑肌细胞内钙增加时，去甲肾上腺素引起的细胞内钙振荡频率明显被抑制。这一新的发现表明，钙通道拮抗剂可以抑制钙离子通道介导的钙信号转导。我们现在正在扩大我们的工作，准备同时测量血管平滑肌细胞和内皮细胞的细胞内钙离子浓度，以研究内皮细胞衍生的松弛因子对血管平滑肌细胞钙离子信号转导的影响。

Using cooled CCD camera or confocal laser scanning microscope, we carried out digital imaging of intracellular Ca^<2+> concentration of vascular smooth muscle cells within intact arterial tissue. Ca^<2+> indicator loaded arterial tissue was mounted in an experimental chamber on the stage of an inverted microscope and stimulated with field electrical stimulation or by solution exchange. We could observe Ca^<2+> concentration change within individual smooth muscle cells, and confirmed our previous results that the intracellular Ca^<2+> concentration change takes place as Ca^<2+> oscillations and waves when the arterial tissue was stimulated with the sympathetic nerve transmitter, noradrenaline. The current experimental system had a greater dynamic range than that in our previous measurements. We studied the effect of dihydropyridine Ca^<2+> channel antagonists on the Ca^<2+> oscillations. In the presence of nicardipine at a concentration enough to inhibit high K-induced intracellular Ca^<2+> increase in vascular smooth muscle cells the frequency of the noradrenaline-induced Ca^<2+> oscillation was significantly inhibited. This new finding suggest that Ca^<2+> channel antagonist can inhibit Ca^<2+> store-mediated Ca^<2+> signalling. We are now expanding our work and preparing for simultaneous measurement of intracellular Ca^<2+> concentrations of vascular smooth muscle cells and endothelial cells to study the effect of endothelium derived relaxing factor on the Ca^<2+> signalling in vascular smooth muscle cells.