有氧运动诱导大鼠胸主动脉平滑肌细胞大电导钙激活钾通道活性增加

Aerobic Exercise Training Activating the Large-conductance Ca^(2+)-activated ~K+ Channels in Rat Thoracic Aorta Smooth Muscle Cells

目的:研究不同频次的规律性有氧运动对大鼠胸主动脉平滑肌细胞大电导钙激活钾通道(BKCa)活性的影响。方法:2月龄雄性Wistar大鼠24只,随机分为安静对照组(SED)、低频有氧运动组(3次/周,EX1)和高频有氧运动组(5次/周,EX2)。12周后取胸主动脉,急性分离动脉平滑肌细胞。应用膜片钳内面向外模式观察运动对其BKCa门控特性的影响。结果:在浴液游离钙离子浓度为1μM时,与SED相比,EX对BKCa单通道电导无显著影响,但可使其开放概率(Po)显著增加,同时通道平均开放时间(To)延长,平均关闭时间(Tc)缩短,且EX2的效应均比EX1显著。结论:长期规律有氧运动可以诱导大鼠胸主动脉平滑肌细胞BKCa通道活性增加,且在运动强度和持续时间一致的情况下,表现出频次依赖特性。

Objective：The purpose of this study was to investigate the effects of aerobic exercise training on the activity of large-conductance Ca2＋-activated K＋ channels（BKCa） in thoracic aorta smooth muscle cells（SMCs）.Methods：Twenty-four 2-month-old male Wistar rats were assigned to 3 groups randomly,sedentary group（SED）,low-frequency exercise group（exercise 3d/w,EX1）,and high-frequency exercise group（exercise 5d/w,EX2）.After 12 weeks,the segment of thoracic aorta was carefully dissected free,and separated into smooth muscle cells by two steps digestion.Results：Inside-out patch clamp recording on aortic SMCs showed that exercise training did not affect the single channel conductance,but significantly increased the open probability（Po） of BKCa channels.Moreover,exercise training decreased the mean closed time（Tc） and increased the mean open time（To） of BKCa channels.This effect was more significant in EX2 group than that in EX1 group.Conclusion：These data suggest that regular aerobic exercise can activate the BKCa channels in the rat thoracic aorta SMCs,which is in a frequency-dependent manner when the intensity and duration of exercise is kept consistent.