Fujimoto S, Yamamoto K, Kuba K, Morita K, Kato E
Brain Res. 1980 Nov 24;202(1):21-32.
The localization of Ca2+ in the bullfrog sympathetic ganglion was studied using electron microscopy with Oschman and Wall's technique. When the ganglion was incubated and processed in an extremely high Ca2+ solution (20 mM) for electron microscopy, electron-dense deposits (EDD) were found at or in the plasma membranes, subsurface cisterns and mitochondria of the postganglionic neurons. These EDD were proved to contain calcium by X-ray microprobe analysis. On the other hand, they were not significant in the preganglionic terminals except those in the synaptic vesicles. Addition of caffeine (10 mM) to the incubation media and fixatives caused a drastic decrease in number of EDD of the subsynaptic membranes and the subsurface cisterns. Caffeine also reduced, but less markedly, the size and number of EDD in mitochondria. Caffeine (10 mM) prolonged the afterhyperpolarization of an action potential, reduced the amplitude of the ACh (nicotinic) potential and induced slow rhythmic hyperpolarizations in a 20 mM Ca2+ solution. These effects of caffeine which were presumably the result of an increase in the intracellular free Ca2+ were discussed in relation to the morphological data.
采用奥施曼和沃尔的技术，利用电子显微镜研究了牛蛙交感神经节中钙离子的定位。当将神经节置于极高钙离子浓度（20 mM）的溶液中孵育并进行电子显微镜处理时，在节后神经元的质膜、表面下池和线粒体处或其中发现了电子致密沉积物（EDD）。通过X射线微探针分析证明这些EDD含有钙。另一方面，在节前终末中，除了突触小泡中的那些，它们并不明显。在孵育培养基和固定剂中添加咖啡因（10 mM）会导致突触后膜和表面下池的EDD数量急剧减少。咖啡因也会减少线粒体中EDD的大小和数量，但不太明显。咖啡因（10 mM）延长了动作电位的超极化后电位，降低了乙酰胆碱（烟碱样）电位的幅度，并在20 mM钙离子溶液中诱导出缓慢的节律性超极化。结合形态学数据讨论了咖啡因的这些作用，推测这些作用可能是细胞内游离钙离子增加的结果。
