海马神经干细胞体外诱导分化过程中延迟整流钾通道的电生理特性

Electrophysiological properties of delayed rectifier outward K ^＋ currents in the differentiation and development of hippocampal neural stem cells

目的研究大鼠海马源神经干细胞（NSC）分化前及其体外诱导分化的神经元样细胞在不同发育阶段延迟整流钾电流（IDR）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。应用膜片钳技术全细胞模式记录IDR的电生理特性。结果IDR的电流密度在NSC分化前和体外分化（DIV）0—6d分别为45pA／pF±4pA／pF和56pA／pF±10pA／pF（＋50mV，标本数=9），而在DIV〉6d的发育过程中保持稳定；InR的半数最大激活膜电位（V1/2）在NSC分化前和DIV0—6d分别为9mV±3mV和12mV±3mV（标本数=9，P〈0．05），激活曲线右移，斜率参数K值无明显改变，但IDR激活特性在DIV〉6d的发育过程中无明显改变；IDR的失活特性NSC分化前后及不同发育阶段的神经元样细胞中均无改变。结论NSC分化／发育过程中，IDR的特性改变均发生在DIV0—6d，提示IDR通道在神经发育过程中发挥作用，且发育初始阶段对于细胞功能的成熟尤为重要。

Objective To study the developmental electrophysiological properties of delayed rectifier outward K ^＋ currents （IDR） in undifferentIAted NSC and NSC-derived neurons at various time points of adult SD rat hippocampus in vitro. Methods Neural stem cells were isolated from the hippocampus of adult SD rats with serum-free incubation and single-cell cloning technique. Electrophysiological recordings of IDR were performed using whole-ceil patch clamp. Results The current density of IDR increased in NSC-derived neurons DIV 0 - 6 d whereas remained constant in DIV 〉 6 d. The current density of IDR at ＋ 50 mV was 45 pA/pF ± 4 pA/pF and 56 pA/pF ± 10 pA/pF in undifferentIA ted NSCs and NSC-derived neurons DIV 0 - 6 d respectively （ n = 9 ） . The activation process of IDR was also altered in DIV 0 - 6 d whereas remained constant in DIV 〉 6 d. The positive shift in steady-state activation curve of IDR revealed an increase of V1/2 , however the slope factors K remained unchanged. V1/2 was 9 mV ＋ 3 mV and 12 mV ＋ 3 mV in undifferentIAted NSCs and NSC-derived neurons DIV 0 -6 d respectively （n = 9, P 〈 0.05 ） The inactivation properties of IDR were not altered before and after differentIA tion. Conclusion Electrophysiological characteristics of IDR were all altered in DIV 0 - 6 d, suggesting the essentIAl role of IDR in neurogenesis and early stage of differentI^tion / development process is very important for the functional mature of neuron.