Relative contributions of passive equilibrium and active transport to the distribution of chloride in mammalian cortical neurons.
Relative contributions of passive equilibrium and active transport to the distribution of chloride in mammalian cortical neurons.
复制标题
被动平衡和主动运输对哺乳动物皮质神经元中氯离子分布的相对贡献。
DOI：
10.1152/jn.1988.60.1.105
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发表时间：
1988
影响因子：
2.5
通讯作者：
Prince,DA
中科院分区：
文献类型：
--
作者：
Thompson,SM;Deisz,RA;Prince,DA
1. 通过体外保存的扣带皮层神经元切片的细胞内记录，评估影响皮层神经元氯梯度的主动和被动因素。氯离子平衡电位（ECl-）是通过对细胞周围γ -氨基丁酸（GABA）和Cl（-）依赖性突触后抑制电位（IPSP）反应的逆转电位间接估计的。在对照条件下，平均静息电位（Vm; -69.7 mV）与平均IPSP逆转电位（EIPSP; -70.1 mV）无显著差异。2. 当外部钾离子浓度（[K+]o）从1 mM增加到10 mM时，平均EIPSP从-80.4 mV增加到-61.8 mV。在所有[K+]个oS中，EIPSP的平均值近似等于Vm的平均值。[K+] 0小于10 mM不满足Donnan平衡条件。在保持电流注入的情况下，Vm在距离EIPSP 20 mV处极化4 min，对EIPSP无显著影响。4. 在用异硫代酸将体外氯离子浓度从133 mM降低到5 mM的生理盐水中平衡后，GABA的逆转电位保持在负37-52 mV以下。在这些条件下记录的细胞Vm和输入电阻与控制值没有显著差异。5. 我们得出结论，Cl-不是被动地分布在皮质神经元中，可能是由于静息时Cl-渗透率低。6. 插入含有2 M KCl的电极导致EIPSP快速的10 mV去极化位移，然后保持相对恒定。细胞内离子导入Cl-导致EIPSP进一步去极化移位5-10 mV，并在不到1 min的时间内恢复到对照状态。IPSP振幅恢复的时间过程可以用一个指数拟合，平均时间常数为6.9 +/- 1.5 s，与Cl-注入量和刺激频率无关。7. 温度从37℃降低到32℃显著提高了注入Cl-后IPSP恢复的平均时间常数，达到11.1 +/- 3.3 s，对应于Q10 = 2.6。（摘要删节为400字）
1. Active and passive factors affecting the chloride gradient of cortical neurons were assessed using intracellular recordings from neurons in slices of cingulate cortex maintained in vitro. The chloride equilibrium potential (ECl-) was estimated indirectly from the reversal potentials of responses to perisomatic gamma-aminobutyric acid (GABA) application and the Cl(-)-dependent inhibitory postsynaptic potential (IPSP). Under control conditions the mean resting potential (Vm; -69.7 mV) was not significantly different than the mean IPSP reversal potential (EIPSP; -70.1 mV). 2. Increasing the external potassium concentration ([K+]o) from 1 to 10 mM shifted the mean EIPSP from -80.4 to -61.8 mV. The mean EIPSP was approximately equal to the mean Vm at all [K+]oS. The conditions of Donnan equilibrium are not met in [K+]o less than 10 mM. 3. Polarization of Vm up to 20 mV away from EIPSP for 4 min with maintained current injection had no significant effect on EIPSP. 4. The GABA reversal potential was maintained 37-52 mV less negative than Vm after equilibration in saline in which the external chloride concentration had been reduced from 133 to 5 mM by substitution with isethionate. Vm and input resistance were not significantly different from control values in cells recorded under these conditions. 5. We conclude that Cl- is not passively distributed in cortical neurons, perhaps due to a low resting Cl- permeability. 6. Impalement with electrodes containing 2 M KCl resulted in a rapid 10 mV depolarizing shift in EIPSP that then remained relatively constant. Intracellular iontophoresis of Cl- resulted in a further depolarizing shift of EIPSP of 5-10 mV that returned to control in less than 1 min. The time course of recovery of IPSP amplitude could be fit with a single exponential having a mean time constant of 6.9 +/- 1.5 s and was independent of the amount of Cl- injected or stimulation frequency. 7. Reductions in temperature from 37 to 32 degrees C significantly increased the mean time constant of IPSP recovery from Cl- injection to 11.1 +/- 3.3 s, corresponding to Q10 = 2.6.(ABSTRACT TRUNCATED AT 400 WORDS)