钾通道阻断剂对低氧/复氧诱导的培养海马神经元死亡的防护作用

Protection of potassium channel inhibitors against hypoxia/reoxygenation-induced death of cultured hippocampal neurons

目的研究钾通道阻断剂对单纯低氧/复氧诱导的培养海马神经元死亡的防护作用。方法培养8 d的海马神经元置于低氧环境(95% N2/5% CO2)6 h,复氧再培养直至72 h,复氧后0.5 h培养液内分别给予不同钾通道阻断剂,用细胞计数及MTT比色法检测神经元死亡情况。结果低氧/复氧诱导培养海马神经元出现迟发性死亡;四乙铵以剂量依赖性的方式防护低氧/复氧诱导的培养海马神经元免于死亡;大电导钙激活钾通道(BK通道)阻断剂iberiotoxin(IbTX)可完全消除低氧/复氧诱导的神经元死亡(P<0.001);A型钾通道阻断剂4-氨基吡啶不能防护低氧/复氧诱导的神经元免于死亡(P>0.05)。结论钾通道阻断剂四乙铵和IbTX能防护低氧/复氧诱导的培养海马神经元免于死亡,提示某些类型的钾通道尤其是BK通道活动增强可能参与了低氧/复氧诱导的培养海马神经元死亡。

Objective To investigate the effects of potassium channel inhibitors on hypoxia/reoxygenation-induced death of cultured hippocampal neurons. Methods Cultured 8 d in vitro, hippocampal neurons were exposed to hypoxia (in mixture of 95% N 2 and 5% CO 2 ) for 6 h, and then reoxygenated till the 72nd hour. Different potassium channel inhibitors were applied to the culture solution separately after reoxygenation. Neuron death was analyzed with cell counting and MTT assay. Results Hypoxia/reoxygenation procedure induced a delayed death of cultured hippocampal neurons. Application of tetraethylammo-nium (TEA) offered concentration-dependent protection of the neurons against death. Selective high-conductance calcium-activated potassium channel (BK) inhibitor iberiotoxin (IbTX) showed significant neuron protection (P<0.001). However, A-type potas-sium channel inhibitor 4-aminopyridine presented no protection against neuron death (P>0.05). Conclusion Following hypoxia/ reoxygenation, enhanced activity of potassium channel, especially BK channel, may induce neuron death.