Patch recordings from the electrocytes of Electrophorus electricus. Na currents and PNa/PK variability.
Patch recordings from the electrocytes of Electrophorus electricus. Na currents and PNa/PK variability.
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DOI：
10.1085/jgp.97.5.1013
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发表时间：
1991-05
影响因子：
3.8
通讯作者：
SIGWORTH, FJ
中科院分区：
文献类型：
--
作者：
SHENKEL, S;SIGWORTH, FJ
在Electrophorus electrocytes神经支配膜的细胞贴附和由内而外的膜片上记录钠电流。如Pasquale等人（1986. J. 93：195）。在室温下，用1-2微米直径的贴片移液管测量的萨克斯器官中的最大电流在20至300 pA（27个贴片）的范围内，并在+10 mV附近获得。该电流范围对应于贴片中的大约70至1，300个通道。主要器官细胞中的最大电流也发生在+10 mV附近，范围为100至400 pA。少数斑片出现延迟钾电流。失活阶段的电流在维持去极化似乎是一个单指数松弛。时间常数从-55 mV附近的1 ms降低到0 mV附近的最小值0.3 ms，然后随着去极化的增强而逐渐增加。平均电流在接近-90 mV时半失活，每6 mV具有e倍的明显电压依赖性。没有明显的差异，观察到在衰减时间过程或稳态失活的电流在同一补丁切除前后。从系综波动分析的峰值开放概率被发现是约0.5在+25 mV和逐渐增加，只有更大的去极化。单通道电导为约20 pS，外部为200 mM Na，内部为200 mM K，在400 mM溶液中为40 pS。在200 Na平行200 K溶液中，多通道贴片的反射电位范围为+51至+94 mV，对应于PNa/PK的选择性比为8至43。甚至在来自同一细胞的贴片之间也可以看到反转电位的巨大差异。几种控制方法排除了反向电位测量中明显的误差来源。它的结论是有异质性的Na通道的选择性特性。
Sodium currents were recorded in cell-attached and inside-out patches from the innervated membrane of Electrophorus electrocytes. Electrocytes from Sachs and main electric organs were prepared as described by Pasquale et al. (1986. J. Membr. Biol. 93:195.). Maximal currents in the Sachs organ, measured with 1-2 microns diameter patch pipettes and at room temperature, were in the range of 20 to 300 pA (27 patches) and were obtained near +10 mV. This range of current corresponds to approximately 70 to 1,300 channels in a patch. Maximal current in main organ cells also occurred near +10 mV and were in the range of 100 to 400 pA. Delayed K current was observed in a few patches. The inactivation phase of the currents during maintained depolarizations appears to be a single-exponential relaxation. The time constant decreases from 1 ms near -55 mV to a minimum of 0.3 ms near 0 mV, and then gradually increases with stronger depolarization. The mean currents are half inactivated near -90 mV with an apparent voltage dependence of e-fold per 6 mV. No apparent differences were observed in the decay time course or steady-state inactivation of the currents in the same patch before and after excision. From ensemble fluctuation analysis the peak open probability was found to be approximately 0.5 at +25 mV and increased only gradually with larger depolarizations. The single channel conductances were approximately 20 pS with 200 mM Na outside and 200 mM K inside, and 40 pS in 400 mM solutions. Reversal potentials in the 200 Na parallel 200 K solutions ranged from +51 to +94 mV in multichannel patches, corresponding to selectivity ratios PNa/PK from 8 to 43. Large differences in reversal potentials were seen even among patches from the same cell. Several controls rule out obvious sources of error in the reversal potential measurements. It is concluded that there is heterogeneity in the selectivity properties of the Na channels.
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DOI：
10.1085/jgp.67.6.621
发表时间：
1976-06
期刊：
The Journal of general physiology
影响因子：
--
作者：
Hagiwara S;Miyazaki S;Rosenthal NP
通讯作者：
Rosenthal NP
影响因子：
3.8
作者：
Cahalan, M;Begenisich, T
通讯作者：
Begenisich, T
DOI：
10.1085/jgp.27.1.37
发表时间：
1943-09-20
期刊：
The Journal of general physiology
影响因子：
--
作者：
Goldman DE
通讯作者：
Goldman DE
影响因子：
5.5
作者：
KEYNES, RD;MARTINSFERREIRA, H
通讯作者：
MARTINSFERREIRA, H
影响因子：
3.8
作者：
GREEN, WN;WEISS, LB;ANDERSEN, OS
通讯作者：
ANDERSEN, OS