运动应激对慢性吸烟大鼠肺动脉平滑肌钾通道BKca及Kv1.5表达的影响

目的观察运动应激对慢性吸烟大鼠肺动脉平滑肌大电导的钙激活的钾通道(BKca)和电压依赖性延迟整流钾通道Kv1.5蛋白和mRNA表达的影响.方法复制大鼠慢性吸烟模型后进行运动训练,测定其血浆中皮质醇浓度,采用HE染色、免疫组织化学染色、原位杂交等方法检测肺组织病理形态学改变和BKca、Kv1.5的表达变化.结果(1)吸烟运动组运动后血浆中皮质醇浓度[(1 528.7±469.7)ng/L]明显高于全部运动训练后次日晨[(672.4±235.7)ng/L],差异有统计学意义(P＜0.01).(2)HE染色显示,吸烟对照组肺组织出现明显的慢性炎症反应,吸烟运动组炎症反应轻于吸烟对照组.(3)吸烟对照组肺动脉BKca mRNA[积分光密度值(OD)值大动脉0.220 6±0.041 5,小动脉0.393 5±0.137 8]和蛋白(OD值大动脉0.263 4±0.121 9,小动脉0.099 5±0.085 1)表达低于正常对照组,吸烟运动组BKca mRNA(OD值大动脉0.502 2±0.113 4,小动脉0.640 8±0.213 5)表达高于吸烟对照组,但对小动脉的蛋白表达无影响.(4)吸烟对照组肺动脉Kv1.5 mRNA(OD值大动脉0.935 4±0.3290,小动脉0.501 2±0.117 0)和蛋白(OD值大动脉1.111 2±0.331 0,小动脉0.473 6±0.1250)表达低于正常对照组,在小动脉吸烟运动组Kv1.5蛋白(OD值0.744 5±0.269 0)高于吸烟对照组,大动脉则无变化.结论适当运动应激可降低慢性吸烟对大鼠肺动脉平滑肌钾通道BKca和Kv1.5表达的抑制作用,运动引起的皮质醇分泌增加可能是其机制之一.

Effect of exercise stress on cigarette smoking induced downregulation of BKca and Kv1.5 expression in pulmonary arterial smooth muscle cells of rats

OBJECTIVE: To investigate the effect of exercise stress on chronic cigarette smoking induced downregulation of large conductance calcium-activated potassium channel (BKca) and voltage-dependent delayed rectifier potassium channel (Kv1.5) expression in pulmonary arterial smooth muscle cells of rats. METHODS: Rats were divided into three groups: the normal control group, the smoking control group and the smoking + exercise group. The plasma cortisol level, the potassium channel expression and the pathological changes in lung tissue were determined with HE staining, the immunohistochemistry and the in-situ hybridization. RESULTS: (1) In the smoking + exercise group, the plasma cortisol level was determined immediately after exercise [(1528.7 +/- 469.7) ng/L] and was higher than that determined before exercise [(672.4 +/- 235.7) ng/L] (P < 0.01); (2) The HE staining showed that the chronic pulmonary inflammatory response in the smoking control group was severe while it was mild in the smoking + exercise group; (3) The mRNA and protein expression (OD value) of BKca in the smoking control group (mRNA: 0.2206 +/- 0.0415 for big artery and 0.3935 +/- 0.1378 for small artery; protein: 0.2634 +/- 0.1219 for big artery and 0.0995 +/- 0.0851 for small artery) were less than those in the normal control group. The mRNA expression of BKca in the smoking + exercise group (OD value) (0.5022 +/- 0.1134 for big artery and 0.6408 +/- 0.2135 for small artery) was higher than that in the smoking control group; (4) The mRNA and protein expression of Kv1.5 in the smoking control group (OD value) (mRNA: 0.9354 +/- 0.3290 for big artery and 0.5012 +/- 0.1170 for small artery; protein: 1.1112 +/- 0.3310 for big artery and 0.4736 +/- 0.1250 for small artery) were less than those in the normal control group. The protein expression of Kv1.5 in the smoking + exercise group (0.7445 +/- 0.2690) in small artery was higher than that in the smoking control group. CONCLUSION: Proper exercise stress can decrease inhibition effect of the chronic smoking on the expression of potassium channel BKca and Kv1.5, which perhaps partly results from exercise induced increase of cortisol secretion.