肌酸补充对葡萄糖剥夺引起的BKca电流变化和胞内游离钙离子浓度的影响
Effect of Creatine Supplymentation on BKca Current Variation and Intracellular Free Calcium Concentration Induced by Glucose Deprivation

摘要：目的：大电导钙激活钾通道（BKCa）对神经元兴奋性以及动作电位发放频率具有重要调控作用。本实验拟观察肌酸补充对皮层神经元葡萄糖剥夺时BKCa电流密度及胞内钙离子浓度的影响。方法：全细胞膜片钳技术记录肌酸干预对不同时长葡萄糖剥夺原代培养大鼠皮层神经元BKCa电流的变化；应用激光共聚焦检测神经元胞内游离钙离子浓度。结果：1）葡萄糖剥夺1～2 h BKCa电流密度显著增加（P < 0.01），4～5 h显著减小（P < 0.01）。胞内游离Ca2+荧光强度随葡萄糖剥夺1～5 h逐渐增强（P < 0.01）；2）肌酸孵育显著减小原代培养神经元BKCa电流密度以及胞内游离Ca2+荧光强度（P < 0.01）。结论：葡萄糖剥夺1～2 h使胞内游离Ca2+浓度显著升高，激活BKCa大量开放，使神经元超极化，降低神经元兴奋性：Cr可有效抑制葡萄糖剥夺引起BKCa电流增加以及胞内钙离子浓度升高，维持锥体神经元的兴奋性。
Abstract: Objective: Large-conductance voltage- and Ca2+-activated K+ channels (BKCa) play important roles in regulating the excitability of neurons and the frequency of action potential release. This study aimed to investigate the effects of creatine supplementation on current density of BKCa in neuronal excitability during glucose deprivation. Methods: The changes of BKCa currents of cortical neurons in primary culture suckling rats with different times glucose deprivation was tested by whole cell patch clamp, and the intracellular free Ca2 + concentration was detected by confocal laser scanning microscopy. Results: 1) The current density of BKCa significantly increased after 1-2h glucose deprivation but decreased after 4-5h glucose deprivation (Ps < 0.01). The concentration of Ca2+ increased over time (1-5h, P < 0.01). 2) Creatine supplementation reduces the current density of BKCa and Ca2+ concentration (P < 0.01). Conclusions: The 1-2h glucose deprivation can improve intracellular free Ca2+ concentration, active BKCa, induce neuronal hyperpolarization and reduce neuronal excitability; Cr can effectively inhibit the increase of BKCa current and intracellular Ca2+ concentration induced by glucose deprivation, and can maintain the excitability of pyramidal neurons