中文摘要：

目的探讨有氧运动训练对衰老大鼠脑动脉平滑肌细胞全细胞K＋电流、自发瞬时外向电流及大电导钙激活钾通道生物物理特性的影响。方法 19~21月龄雄性Wistar大鼠12只（老年组）,随机分为安静组和有氧运动组,并选用2月龄Wistar大鼠安静处理作为青年对照组。12周后取脑动脉,急性分离动脉平滑肌细胞。分别采用膜片钳全细胞模式、穿孔膜片钳模式和单通道内面向外模式观察运动对全细胞K＋电流、自发瞬时外向电流和大电导钙激活钾通道门控特性的影响。结果安静组全细胞K＋电流密度及对Iberiotoxin敏感性降低;安静组自发瞬时外向电流幅值降低,频率无明显变化;安静组大电导钙激活钾通道平均开放概率和平均开放时间显著低于青年对照组,而平均关闭时间高于青年对照组;电压依赖性和钙敏感性亦显著下降;与安静组相比,有氧运动可以增加全细胞K＋电流密度、自发瞬时外向电流幅值及大电导钙激活钾通道平均开放概率、电压依赖性和钙敏感性来实现对大鼠脑动脉平滑肌自发瞬时外向电流/大电导钙激活钾通道功能的保护作用。结论长期规律有氧运动可以减弱衰老所致的大鼠脑动脉平滑肌细胞大电导钙激活钾通道功能下调,这可能是有氧运动改善衰老动脉功能的重要机制之一。

英文摘要：

Aim To determine the effects of aerobic exercise training on aging-associated selective changes of the function of the spontaneous transient outward currents and the large-conductance Ca2 ＋-activated K＋channels in cerebral arteries.Methods Male Wistar rats aged 19 ~ 21 months were randomly assigned to sedentary（O-SED） and exercisetrained groups（O-EX）.Two-month-old rats were used as Young control.After 12 weeks,the segment of cerebral arteries was carefully dissected free,and separated into smooth muscle cells by two steps digestion.Results Whole-cell patch clamp showed that aging decreased the density of whole-cell K＋current and iberiotoxin-sensitive whole-cell K＋current; The amplitude of spontaneous transient outward currents was decreased by aging,while there was no significant difference in the frequency; Inside-out patch clamp recording on cerebral arteries myocytes showed that aging decreased the open probability and Ca2 ＋/ voltage sensitivity of single large-conductance Ca2 ＋-activated K＋channel; The opening time was decreased by aging,whereas the close time was increased.However,exercise training inhibited all of these changes.Conclusion These data suggest that regular aerobic exercise can attenuate the functional downregulation of spontaneous transient outward currents / large-conductance Ca2 ＋-activated K＋channels in aging cerebral arteries myocytes,which may be one of the important mechanisms underlying the beneficial effects of aerobic exercise on aging arteries.