Characterization of sodium current in developing rat diencephalic neurons in serum-free culture.
Characterization of sodium current in developing rat diencephalic neurons in serum-free culture.
复制标题
无血清培养中发育中的大鼠间脑神经元钠电流的表征。
DOI：
10.1152/jn.1991.65.5.1011
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发表时间：
1991
影响因子：
2.5
通讯作者：
Ahmed,Z
中科院分区：
文献类型：
--
作者：
Park,CC;Ahmed,Z
1.分离的、同步化的(细胞周期的G1期)胎鼠间脑神经元在无血清培养条件下培养。采用巨细胞全细胞电压钳技术，对形态鉴定的双极神经元进行内向Na+电流(INa)的测定。最早表达的体细胞INA已经被鉴定，并与现在的相比较。2.根据河豚毒素(TTX)的可逆性阻断和逆转电位，确定了INA的特性。在两种不同的Na+浓度(分别为120 mM和35 mM)下，测量的翻转电位(68.5+/-1.3和38.3+/-2.4 mV)与计算的能斯特平衡电势(64.6和34.7 mV)非常接近，表明该通道对Na+具有很高的选择性。3.INa峰值密度从年轻神经元(培养5-6天)的47.7+/-2.9 pA/pF增加到老年神经元(培养12-13天)的93.9+/-6.4 pA/pF。激活电压和峰值电流电压也在超极化方向上移动了10 mV，从年轻神经元的-30 mV和+10 mV分别移动到老年神经元的-40 mV和0 mV。然而，翻转电位没有改变(年轻神经元和老年神经元分别为69.2+/-2.3和68.5+/-1.3 mV)。4.在老年神经元中，稳态失活参数(V1/2，失活为最大值的50%的电压，以及kh，失活发生e倍变化的电压)显著改变。V1/2由-41.5+/-2.3移至-48.8+/-1.8 mV，Kh由6.2+/-0.5 mV增加至8.9+/-0.4 mV。然而，激活的时间进程以及失活和失活恢复率没有变化。5.在两组中，INA衰变最好用两个指数之和来描述。相应的时间常数与电压有关。此外，膜电位和尼氟米酸对这两种成分的幅度也有不同的影响。6.老年神经元INA快、慢成分的波幅外推均较大，但两者的波幅比值不随年龄变化。改变了两个组件的时间常数的电压依赖关系。7.我们得出结论，在只含必需营养素的特定培养液中生长的胎鼠间脑神经元的INA在体外经历了电流密度和部分(但不是全部)动力学参数的变化。
1. Dissociated, synchronized (G1 phase of cell cycle), and birth-dated fetal rat diencephalic neurons were grown in a serum-free defined medium. The gigaseal whole-cell voltage-clamp technique was used to measure the inward Na+ currents (INa) from morphologically identified bipolar neurons. The earliest expressed somatic INa has been characterized and compared with that present at a later date. 2. The identity of the INa was established on the basis of its reversal potential and reversible blockade by tetrodotoxin (TTX). Close agreement between the measured reversal potentials (68.5 +/- 1.3 and 38.3 +/- 2.4 mV, mean +/- SE) and calculated Nernst equilibrium potentials (64.6 and 34.7 mV) at two different bath Na+ concentrations (120 and 35 mM, respectively) suggests that the channels are highly selective for Na+. 3. The peak INa density increased from 47.7 +/- 2.9 pA/pF in younger neurons (5-6 days in culture) to 93.9 +/- 6.4 pA/pF in older neurons (12-13 days in culture). The activation voltage and the voltage for peak current were also shifted by 10 mV in the hyperpolarizing direction, from -30 and +10 mV in younger neurons to -40 and 0 mV in older neurons, respectively. However, the reversal potential did not change (69.2 +/- 2.3 and 68.5 +/- 1.3 mV in younger and older neurons, respectively). 4. In older neurons the steady-state inactivation parameters (V1/2, the voltage at which inactivation was 50% of maximum, and kh, the voltage at which there is an e-fold change in inactivation) were significantly altered. V1/2 was shifted from -41.5 +/- 2.3 to -48.8 +/- 1.8 mV, and kh was increased from 6.2 +/- 0.5 to 8.9 +/- 0.4 mV. However, the time course of activation and the rates of inactivation and recovery from inactivation were unchanged. 5. In both groups, the INa decays were best described by a sum of two exponentials. The corresponding time constants were voltage dependent. Also, the amplitudes of the two components were differentially affected by membrane potential and niflumic acid. 6. The extrapolated amplitudes of both the fast and the slow components of INa were larger in older neurons, but the ratio of the amplitudes of the two components did not change with age. The voltage dependencies of the time constants of both components were altered. 7. We conclude that INa in fetal rat diencephalic neurons grown in a defined medium with only essential nutrients undergoes in vitro changes in current density and in some, but not all, kinetic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)