Kühtreiber W M, Jaffe L F
Marine Biological Laboratory, Woods Hole, Massachusetts 02543.
J Cell Biol. 1990 May;110(5):1565-73. doi: 10.1083/jcb.110.5.1565.
We have developed a vibrating calcium-specific electrode to measure minute extracellular calcium gradients and thus infer the patterns of calcium currents that cross the surface of various cells and tissues. Low-resistance calcium electrodes (routinely approximately 500 M omega) are vibrated by means of orthogonally stacked piezoelectrical pushers, driven by a damped square wave at an optimal frequency of 0.5 Hz. Phase-sensitive detection of the electrode signal is performed with either analogue or digital electronics. The resulting data are superimposed on a video image of the preparation that is being measured. Depending on the background calcium concentration, this new device can readily and reliably measure steady extracellular differences of calcium concentration which are as small as 0.01% with spatial and temporal resolutions of a few microns and a few seconds, respectively. The digital version can attain a noise level of less than 1 microV. In exploratory studies, we have used this device to map and measure the patterns of calcium currents that cross the surface of growing fucoid eggs and tobacco pollen, moving amebae and Dictyostelium slugs, recently fertilized ascidian eggs, as well as nurse cells of Sarcophaga follicles. This approach should be easily extendable to other specific ion currents.
我们开发了一种振动式钙特异性电极，用于测量微小的细胞外钙梯度，从而推断穿过各种细胞和组织表面的钙电流模式。低电阻钙电极（通常约为500兆欧）通过正交堆叠的压电推动器振动，由频率为0.5赫兹的阻尼方波驱动。电极信号的相敏检测通过模拟或数字电子设备进行。所得数据叠加在正在测量的标本的视频图像上。根据背景钙浓度，这种新设备能够轻松可靠地测量细胞外钙浓度的稳定差异，其差异小至0.01%，空间分辨率和时间分辨率分别为几微米和几秒。数字版本的噪声水平可低于1微伏。在探索性研究中，我们使用该设备绘制并测量了穿过生长中的岩藻卵和烟草花粉表面、移动的变形虫和盘基网柄菌蛞蝓、刚受精的海鞘卵以及肉蝇卵泡滋养细胞表面的钙电流模式。这种方法应该很容易扩展到其他特定的离子电流。
