8周跑台运动对高血压大鼠血压调节和脑内血管紧张素转换酶的影响

目的:观察8周跑台运动对自发性高血压大鼠血压、血压调节功能和心血管中枢血管紧张素转换酶活性和基因表达的影响,探讨运动训练改善血压调节功能的中枢机制。方法:6周龄雄性自发性高血压大鼠(SHR)随机分成安静组(S)和运动组(E),正常血压WKY大鼠作为对照组(C),每组10只。运动组大鼠进行8周中低强度跑台运动,尾套法测定收缩压和心率。药物法检测压力反射敏感性(BRS)代表血压调节功能。用荧光定量PCR和酶联免疫吸附法检测心血管中枢延髓头端腹外侧区(RVLM)、孤束核(NTS)、室旁核(PVN)]血管紧张素转换酶(ACE)和血管紧张素转换酶2(ACE2)基因表达和酶活性。结果:①8周运动结束,14周龄SHR安静组收缩压显著高于同龄WKY-C组,运动训练明显降低SHR血压和心率,改善血压调节能力,阻止压力反射功能降低,SHR血压与BRS呈负相关。②SHR安静组RVLM和PVN的ACE基因表达和酶活性显著高于WKY-C组,但ACE2基因表达和酶活性低于WKY-C组,8周运动逆转上述变化。③SHR大鼠BRS与心血管中枢ACE酶活性负相关、与ACE2酶活性呈正相关。结论:8周跑台运动降低高血压、改善血压调节功能可能与运动恢复中枢ACE/ACE2平衡有关。

Effects of 8 weeks treadmill exercise on blood pressure regulation and angiotensin converting enzyme in the brain of hypertensive rats

Objective: To investigate effects of 8 weeks treadmill exercise on blood pressure, blood pressure regulation,gene expression and activity of angiotensin converting enzyme(ACE) and ACE2 in the cardiovascular centers of spontaneously hypertensive rats.Method: Male 6-wk SHR were randomly assigned into sedentary group(SHR-S, n=10) and exercise-trained group(SHR-E, n=10). Ten gender-and age-matched Wistar Kyoto rats(WKY) were used as a control group(WKY-C, n=10). The trained rats ran on a treadmill in a moderate intensity for 8 weeks. Systolic blood pressure(SBP) and heart rate(HR) were measured by a tail-cuff method. The baroreflex sensitivity(BRS) was assessed by intravenous injection of phenylephrine. The mRNA of angiotensin converting enzyme(ACE) and angiotensin converting enzyme 2(ACE2) in the cardiovascular centers were detected by real-time PCR. Enzymelinked immunosorbent assay(ELISA) was used to measured enzyme activity of ACE and ACE2.Result:①After 8 weeks exercise, SHR-S rats had higher SBP than that in WKY-C group. However, exercise training significantly reduced SBP and HR, improved blood pressure regulation function, and prevented a decrease in BRS in SHR. Furthermore, there was a negative correlation between SBP and BRS in SHR.②ACE activity and gene expression were greatly enhanced whereas ACE2 activity and gene expression were inhibited in SHR-C group compared with WKY-C group.However,8 weeks of exercise training reversed those alterations.③BRS in SHR was negatively correlated with ACE activity in cardiovascular centers, but positively correlated with ACE2 activity.Conclusion: Eight weeks treadmill exercise significantly decreases hypertension and improves blood pressure regulation function in SHR, which maybe associated with restoration of central ACE and ACE2 balance evoked by exercise training.