Analysis of calcium oscillations in vascular smooth muscle cells

利用冷却CCD相机或共聚焦激光扫描显微镜对完整动脉组织内血管平滑肌细胞内Ca^<2+>浓度进行了数字成像。将装载Ca^<2+>指示剂的动脉组织置于倒置显微镜台上的实验室内，用场电刺激或溶液交换刺激。我们可以观察到单个平滑肌细胞内Ca^<2+>浓度的变化，证实了我们之前的结果，即当交感神经递质去甲肾上腺素刺激动脉组织时，细胞内Ca^<2+>浓度的变化是以Ca^<2+>振荡和波的形式发生的。当前实验系统的动态范围比我们以前测量的要大。我们研究了二氢吡啶类Ca^<2+>通道拮抗剂对Ca^<2+>振荡的影响。当硝地平浓度足以抑制高钾诱导的血管平滑肌细胞内Ca^<2+>升高时，去甲肾上腺素诱导的Ca^<2+>振荡频率被显著抑制。这一新发现表明Ca^<2+>通道拮抗剂可以抑制Ca^<2+>储存介导的Ca^<2+>信号传导。我们正在扩大我们的工作范围，准备同时测量血管平滑肌细胞和内皮细胞的细胞内Ca^<2+>浓度，以研究内皮来源的松弛因子对血管平滑肌细胞Ca^<2+>信号的影响。

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.