PHYSIOLOGICAL ROLE OF NEURONAL-GRIAL INTERACTION

Schwann Cells是从squid giant axons中分离的。Macroscopic ionic currents使用全细胞钳记录，使用补丁钳记录单通道currents。两种类型的离子电流被发现与整个细胞电压钳。One is voltage gated L-type calcium current sensitive to externally applied nifedipine or Coy D12+イエD1。此当前激活时间为>-40mV。另一个当前是被过度记录的马铃薯当前。此当前是由外部应用的尼夫皮汀或CO-D12 +-D1封闭的，但对外部应用的咖啡因、亚麻丁或L-谷氨酸盐不敏感。单电位信道电流具有40 pS的导电性，该电流被记录在极好的内而外补丁中。The open？ability（Po） was 0.05 at 3 x10？D1-7？D1M Ca？D12+？D1， increased transiently to 0.4 when the Ca？D12+？D1 concentration was elevated to 1×10？D1-6？D1M， then？down spontaneously at this Ca？D12+？D1 concentration。渠道活动对L-谷氨酰胺、内部应用乙酰胆碱素（ACh）或ATP不敏感。结果建议Calcium activated Potassium Channels在生成-40mV的Schwann细胞膜潜力中发挥基本作用，而膜潜力由intracellular Ca D12+ Yie D1级控制。Schwann cells were loaded fluo-3， a Ca y D12+ y D1敏感染料。Externally applied K+ induced an increase in the internal Ca D12+ y D1 level only when external solution contained Ca D12+ y D1。外部应用的L-葡萄糖、ACh和咖啡因在内部Ca-D12 + Ca-D1级别上没有检测到的变化。

Schwann cells were enzymatically isolated from squid giant axons. Macroscopic ionic currents were recorded using whole cell clamp and single channel currents using patch clamp. Two types of ionic currents were found with whole cell voltage clamp. One is voltage gated L-type calcium current sensitive to externally applied nifedipine or CoィイD12+ィエD1. This current is activated at >-40 mV. The other current is outwardly rectified potassium current. This current is blocked by externally applied nifedipine or COィイD12+ィエD1, but insensitive to externally applied caffeine, ryanodine or L-glutamate. Single potassium channel currents with a conductance of 40 pS were recorded from excised inside-out patches. The open probability (Po) was 0.05 at 3x10ィイD1-7ィエD1 M CaィイD12+ィエD1, increased transiently to 0.4 when the CaィイD12+ィエD1 concentration was elevated to 1×10ィイD1-6ィエD1 M, then ran down spontaneously at this CaィイD12+ィエD1 concentration. The channel activity was insensitive to externally applied L-glutamate, internally applied acetylcholine (ACh), or ATP. The results suggest that the calcium activated potassium channels play an essential role in generation of the Schwann cell membrane potential of -40 mV, and the membrane potential is controlled by the intracellular CaィイD12+ィエD1 level. Schwann cells were loaded fluo-3, a CaィイD12+ィエD1-sensitive dye. Externally applied K+ induced an increase in the internal CaィイD12+ィエD1 level only when external solution contained CaィイD12+ィエD1. Externally applied L-glutamate, ACh, and caffeine induced no detectable change in the internal CaィイD12+ィエD1level.