映山红花总黄酮对大鼠神经元及EA.hy926内皮细胞超极化作用及机制

Effect and mechanism of total flavones of rhododendra on membrane hyperpolarization in rat hippocampal neurons and EA. hy926 cells

目的:观察映山红花总黄酮(total flavones of rhododendra,TFR)对大鼠海马神经元及EA.hy926内皮细胞膜超极化作用及机制研究。方法:体外培养大鼠海马神经元和EA.hy926内皮细胞,利用Di BAC_4(3)荧光染料在钙离子成像系统488 nm激发波长下检测EA.hy926和大鼠海马神经元荧光强度变化以反映膜电位改变情况。结果:与Control组比较,TFR(270 mg/L)和TFR(810 mg/L)能显著降低EA.hy926内皮细胞内荧光强度,即细胞发生了超极化现象,且BK_(Ca)特异性阻断剂Ib TX及联用IK_(Ca)阻断剂Ch TX和SK_(Ca)阻断剂apamin均能抑制TFR(270 mg/L)引起的荧光强度降低现象,而内源性硫化氢(hydrogen sulphide,H_2S)合成酶抑制剂DL-炔丙基甘氨酸(DL-propargylglycine,PPG)对这一超极化效应无显著影响;与Control组比较,TFR(270 mg/L)和TFR(810 mg/L)也能显著降低大鼠海马神经元荧光强度,且Ib TX能抑制TFR(270 mg/L)引起的荧光强度降低现象。结论:TFR可引起大鼠海马神经元和EA.hy926细胞膜超极化,其作用机制可能与激活细胞膜上钙激活钾通道(Ca^(2+)-sensitive K^+ channels,K_(Ca))有关。

AIM： To observe the effect and mechanism of total flavones of rhododendra（ TFR）on membrane hyperpolarization in rat hippocampal neurons and EA. hy926 vascular endothelial cells.METHODS： Rat hippocampal neurons and EA.hy926 cells were cultured in vitro; the changes in fluorescence intensity of endothelial cells and rat neurons were measured by Di BAC4（3） fluorescent dyes through the calcium ion imaging system with the excitation wavelength of 488 nm to reflect the membrane potential. RESULTS： Compared with control group,TFR（ 270 mg/L and 810 mg/L）could markedly reduce intensity of fluorescence in EA. hy926 cells,and the effect could be inhibitedby BK_（Ca） specific inhibitor Ib TX,the co-application of IK_（Ca）inhibitor Ch TX and SK_（Ca）inhibitor apamin,while DL-propargylglycine（ PPG） couldn ＇ t; Compared with Control group,TFR（270 mg/L and 810mg/L） could obviously reduce the intensity of fluorescence in rat hippocampal neurons and this effect could also be blocked by Ib TX. CONCLUSION：TFR can cause membrane hyperpolarization in EA.hy926 cells and rat hippocampal neurons; the possible mechanism is related to activating K_（Ca）channels.