大鼠海马神经干细胞外向电压门控性钾通道的电生理特性

目的 研究大鼠海马源神经干细胞(NSC)外向电压门控性钾通道(Kv)的电生理特性.方法 利用无血清培养、单细胞克隆技术,体外培养SD大鼠海马组织源NSC.以免疫细胞化学方法对NSC及其分化后的子代神经细胞进行鉴定.应用膜片钳技术全细胞模式记录不同外向Kv通道的电生理特性.结果 体外培养SD大鼠海马组织源NSC表达巢蛋白(nestin),在体外可诱导分化产生分别表达Tuj1和GFAP的细胞.全细胞膜片钳可记录到三种外向Kv通道:一种缓慢激活的、对四乙基胺(TEA)敏感的延迟整流钾电流(IDR);一种快速激活和失活、可被4-氨基吡啶(4-AP)阻断的外向瞬时钾电流(IA),其在+20 mV和+50 mV的电流密度分别为11 pA/pF±3 pA/pF和29 pA/pF ±7 pA/pF(标本数=11);一种可被iberiotoxin(IbIX)抑制的大电导钙激活钾通道(BKCa),钳制电位+80mV时,加入100 nM IbTX前后的电流密度分别为56 pA/pF ±4 pA/pF和45 pA/pF±4 pA/pF(标本数=6.P＜0.05).结论 体外培养的未分化状态下SD大鼠海马源NSC至少含有IDR、IA和BKCa三种外向Kv通道.

Electrophysiological properties of outward voltage-gated potassium channels of neural stem cells from adult rat hippocampus

OBJECTIVE: To explore the electrophysiological properties of outward voltage-gated potassium channels of neural stem cells (NSCs) from adult rat hippocampus. METHODS: NSCs were isolated from the hippocampus of adult SD rats with serum-free incubation and single-cell cloning technique. Immunochemistry technique was employed to identify the clone cells and clone cell-derived progeny. Electrophysiological recordings of various outward voltage-gated potassium channels were performed at room temperature using whole-cell patch clamp. RESULTS: The floating neural spheres from the hippocampus showed the expression of nestin antigen, and were able to differentiate into neural cells expressing Yuj1 antigen and glial fibrillary acidic protein (GFAP) respectively in vitro. Three type specialized ion channels were find in cultured NSCs: The outward delayed rectifier outward K(+) currents (I(DR)) was characterized by a slow activation with depolarization and a sensitivity to tetraethylammonium (TEA). The current density of transient A type K(+) currents (I(A)) was 11 pA/pF +/- 3 pA/pF and 29 pA/pF +/- 7 pA/pF (n = 11) at +20 mV and +50 mV respectively, which was characterized by a rapid activation with depolarization and could be blocked by 4-AP. The large conductance calcium activated potassium (BKCa) channels was identified by the inhibition of iberiotoxin (IbTX). The current density of this channel at +80 mV was 56 pA/pF +/- 4 pA/pF and 45 pA/pF +/- 4 pA/pF (n = 6, P < 0.05) before and after application of 100 nM IbTX respectively. CONCLUSION: The cultured NSCs of adult rat hippocampus express at least three kinds of outward voltage-gated potassium channels, I(DR), I(A), and BKCa in vitro.