Photobleaching through glass micropipettes: sodium channels without lateral mobility in the sarcolemma of frog skeletal muscle.
Photobleaching through glass micropipettes: sodium channels without lateral mobility in the sarcolemma of frog skeletal muscle.
复制标题
通过玻璃微量移液器进行光漂白：青蛙骨骼肌肌膜中没有横向移动性的钠通道。
DOI：
10.1073/pnas.79.3.946
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发表时间：
1982
影响因子：
11.1
通讯作者：
Almers,W
中科院分区：
文献类型：
--
作者：
Stühmer,W;Almers,W
通过使用火抛光的微量移液器对一小块肌膜进行电隔离和电压钳位，记录青蛙骨骼肌的钠电流。钠电流振幅用于测定贴片中功能性钠通道的数量。使用移液管作为光导，用通过石英光纤引导到移液管后端的紫外 (UV) 光照射这些通道。从移液管尖端发出的紫外线导致贴片中钠通道的局部破坏，在 30-90 秒的照射期间将钠电流减少 3 至 5 倍。如果钠通道可以在膜中横向扩散，则当新鲜通道从邻近区域进入时，来自贴片的电流应随时间恢复。照射后观察1小时期间未观察到这种恢复。我们的结果将扩散系数的上限设定为 10(-12) cm2/s——视紫红质（视网膜杆细胞膜中的一种膜蛋白）的扩散系数的 1/1000。有人认为钠通道锚定在肌膜中。
Sodium currents were recorded from frog skeletal muscle by using fire-polished micropipettes to electrically isolate and voltage clamp a small patch of sarcolemma. Sodium current amplitude served as an assay for the number of functional sodium channels in the patch. With the pipette as a light guide, these channels were irradiated with ultraviolet (UV) light directed through a quartz fiber into the back end of the pipette. The UV light emerging from the pipette tip caused localized destruction of the sodium channels in the patch, reducing sodium current 3- to 5-fold during a 30-90 s irradiation. If sodium channels could diffuse laterally in the membrane, current from the patch should recover with time as fresh channels enter from neighboring areas. No such recovery was observed during observation for 1 hr after irradiation. Our results set an upper limit of 10(-12) cm2/s for the diffusion coefficient--1/1000th that of rhodopsin, a membrane protein in the cell membrane of retinal rods. It is suggested that sodium channels are anchored in the sarcolemma.