Nealey T, Spires S, Eatock R A, Begenisich T
Department of Physiology, University of Rochester Medical Center, New York 14642-8642.
J Membr Biol. 1993 Feb;132(1):13-25. doi: 10.1007/BF00233048.
The squid giant axon is formed from the fusion of many axons whose cell bodies are located in the giant fiber lobe (GFL) of the stellate ganglion. We measured macroscopic potassium channel currents in both squid giant axons and in the cell bodies. These currents appear similar in many ways, but were differently affected by the amino group modifying reagent, trinitrobenzene sulfonic acid (TNBS). TNBS increased the steady-state amplitude of the axonal currents but decreased the somal currents. We also studied single K channel currents in the giant fiber lobe cells, for comparison with single K channel currents measured previously in the axons. We found two common classes of K channels, distinguished by their conductances (11 and 25 pS) and kinetic properties. The two channel types resemble the 10 and 20 pS channels that have been described in squid giant axons. These results suggest that the cell bodies and axons express fundamentally similar K channel types. The different effects of amino group modification on macroscopic K currents in the two regions may arise from small (perhaps posttranslational) modifications of the core proteins.
鱿鱼的巨大轴突是由许多轴突融合形成的，这些轴突的细胞体位于星状神经节的巨大纤维叶（GFL）中。我们测量了鱿鱼巨大轴突和细胞体中的宏观钾通道电流。这些电流在许多方面看起来相似，但受到氨基修饰试剂三硝基苯磺酸（TNBS）的影响不同。TNBS增加了轴突电流的稳态幅度，但降低了细胞体电流。我们还研究了巨大纤维叶细胞中的单个钾通道电流，以便与先前在轴突中测量的单个钾通道电流进行比较。我们发现了两类常见的钾通道，根据它们的电导（11和25 pS）和动力学特性来区分。这两种通道类型类似于在鱿鱼巨大轴突中描述的10和20 pS通道。这些结果表明，细胞体和轴突表达基本相似的钾通道类型。氨基修饰对两个区域宏观钾电流的不同影响可能源于核心蛋白的微小（可能是翻译后）修饰。
