Passafaro M, Clementi F, Pollo A, Carbone E, Sher E
Department of Medical Pharmacology, University of Milan, Italy.
Neuron. 1994 Feb;12(2):317-26. doi: 10.1016/0896-6273(94)90274-7.
125I-omega-conotoxin binding to neuroblastoma cells at 37 degrees C continuously increased, reaching a plateau after 6-8 hr; this was up to 6 times higher than that observed at lower temperatures. The same effect was induced by short pulses with omega-conotoxin followed by a chase period at 37 degrees C in control medium. Cd2+ also induced up-regulation of surface 125I-omega-conotoxin-binding sites. Fura-2 and patch-clamp experiments showed that the recruited binding sites corresponded to functional voltage-operated Ca2+ channels. Permeabilization experiments revealed a large intracellular pool of 125I-omega-conotoxin-binding sites, whose recruitment to the plasmamembrane was prevented by brefeldin A and nocodazole. These data suggest that specific stimuli might induce voltage-operated Ca2+ channel translocation to plasmamembrane and, in this way, modulate presynaptic events.
125I-ω-芋螺毒素在37℃下与神经母细胞瘤细胞的结合持续增加，6-8小时后达到平台期；这比在较低温度下观察到的结合量高出6倍。用ω-芋螺毒素短脉冲处理后，在37℃的对照培养基中进行追踪培养，也能诱导相同的效应。Cd2+也能诱导表面125I-ω-芋螺毒素结合位点的上调。Fura-2和膜片钳实验表明，新募集的结合位点对应于功能性电压门控Ca2+通道。透化实验揭示了细胞内存在大量125I-ω-芋螺毒素结合位点，布雷菲德菌素A和诺考达唑可阻止这些位点募集到质膜上。这些数据表明，特定刺激可能诱导电压门控Ca2+通道转位到质膜，从而调节突触前事件。
