Differences in voltage-dependent sodium currents exhibited by superficial and deep layer neurons of guinea pig entorhinal cortex.
Differences in voltage-dependent sodium currents exhibited by superficial and deep layer neurons of guinea pig entorhinal cortex.
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豚鼠内嗅皮层浅层和深层神经元表现出的电压依赖性钠电流的差异。
DOI：
10.1152/jn.1994.71.5.1986
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发表时间：
1994
影响因子：
2.5
通讯作者：
Wong,RK
中科院分区：
文献类型：
--
作者：
Fan,S;Stewart,M;Wong,RK
1.采用全细胞电压钳技术研究了豚鼠内嗅皮层浅层（II/III）和深层（V/VI）神经元的钠电流。2.在相同条件下，浅层细胞中的钠电流（峰值幅度）大于深层细胞中的钠电流：-1939 +/- 780（SD）pA（N = 6）对比-307 +/- 257 pA（N = 6）。比膜电导计算为12.3 +/- 9.6 mS/cm 2的浅层细胞和1.4 +/- 0.9 mS/cm 2的深层细胞。3.去极化电位为-20 mV时，浅层细胞可激活钠电流，而去极化电位大于-50 mV时，深层细胞无明显钠电流激活。使用由25 ms预脉冲和20 ms测试脉冲组成的方案，发现浅层细胞的失活曲线向更去极化的电位移动平均15 mV（V50 = -59.8 +/- 3.8 mV，而深层细胞为-75.7 +/- 12.0 mV）。这产生了与表面细胞的激活曲线重叠的区域。4.在约-50至-20 mV的范围内，在表层细胞中，激活和失活曲线的重叠区域，可以激活钠电流，其在测试脉冲期间没有完全衰减（平均峰值振幅：-89.5 +/- 48.7 pA;交叉电压：-39.2 +/- 2.0 mV）。电压步骤，以更多的去极化电位，电压“窗口”之外，允许完全失活的钠电流。（250字处删节）
1. Sodium currents were studied using whole-cell voltage-clamp techniques in neurons acutely isolated from superficial (II/III) and deep (V/VI) layers of guinea pig entorhinal cortex. 2. Sodium currents were larger (peak amplitude) in superficial than in deep layer cells under the same conditions: -1939 +/- 780 (SD) pA (N = 6) versus -307 +/- 257 pA (N = 6). Specific membrane conductance was calculated to be 12.3 +/- 9.6 mS/cm2 for superficial layer cells and 1.4 +/- 0.9 mS/cm2 for deep layer cells. 3. Sodium currents could be activated in superficial layer cells from potentials as depolarized as -20 mV, whereas no significant currents could be activated in deep neurons from potentials more depolarized than about -50 mV. Using a protocol consisting of a 25-ms prepulse and a 20 ms test pulse, the inactivation curves for superficial layer cells were found to be shifted toward more depolarized potentials by an average of 15 mV (V50 = -59.8 +/- 3.8 mV compared with -75.7 +/- 12.0 mV for deep cells). This produced a region of overlap with the activation curves for superficial cells. 4. Over a range of about -50 to -20 mV in superficial layer cells, the region of overlap of the activation and inactivation curves, a sodium current could be activated, which did not fully inactivate during the test pulse (average peak amplitude: -89.5 +/- 48.7 pA; crossover voltage: -39.2 +/- 2.0 mV). Voltage steps to more depolarized potentials, outside the voltage “window”, permitted complete inactivation of the sodium current.(ABSTRACT TRUNCATED AT 250 WORDS)