有氧运动对衰老大鼠肠系膜动脉平滑肌细胞自发瞬时外向流的影响

Effects of aerobic exercise on the spontaneous transient outward currents in aging mesenteric arterial smooth muscle cells

目的探讨有氧运动对衰老大鼠肠系膜动脉平滑肌细胞自发瞬时外向流(STOCs)的影响及可能机制。方法 19~21月龄雄性Wistar大鼠,随机分为安静组(O-SED)和有氧训练组(O-EX);另选2月龄大鼠作为青年对照组(Young)。采用穿孔膜片钳技术对细胞STOCs进行记录。结果 STOCs具有明显的电压依赖性;在相同钳制电位下,STOCs的幅值和频率均Young组>O-EX组>O-SED组。蛋白免疫印迹分析显示衰老细胞BKCa的α和β1亚基表达均下降,而有氧运动显著抑制此变化。结论衰老可诱发大鼠肠系膜动脉平滑肌细胞BKCa的亚基下调,从而使STOCs减弱、膜去极化和外周阻力增加;而规律性有氧运动可显著抑制此变化,这可能是运动诱导衰老血管逆重构、缓解血管张力增高的重要机制。

Objective To determine the effects of aerobic exercise training on the spontaneous transient outward currents( STOCs)in aging mesenteric arterial smooth muscle cells. Methods Male Wistar rats aged 19 ~ 21 months were randomly assigned to sedentary( OSED) and exercise-trained groups( O-EX). Two-month-old rats were used as young control. STOCs were recorded by perforated whole-cell patch-clamp technique. Results STOCs were voltage-dependent. At the same holding potential,both amplitude and frequency of STOCs in mesenteric arteries were Young > O-EX > O-SED. Western blot revealed that the protein expression of the large-conductance Ca2 +-activated K + channels( BKCa) was significantly reduced with aging. However,exercise training diminished this alteration. Conclusions Aging could induce the downregulation of the molecular expression of the BKCa subunits in mesenteric arterial smooth muscle cells,which leads to the decrease of the STOCs,membrane depolarization,and the increase of the peripheral resistance. However,regular aerobic exercise could attenuate these aging-associated changes,which might be one of the important mechanisms underlying the beneficial effects of aerobic exercise on aging arterial remodeling and tension increase.