CaMKⅡδ在有氧运动调控高血压心肌细胞凋亡中的作用

关键词：有氧运动  钙/钙调素依赖性蛋白激酶δ亚型  高血压  心肌细胞  凋亡

Keywords:aerobic exercise  calcium/calmodulin-dependent protein kinase Ⅱδ  hypertension  cardiomyocytes  apoptosis

摘要：

      摘要 目的：探讨Ⅱ型钙/钙调素依赖性蛋白激酶δ亚型（calcium/calmodulin-dependent protein kinase Ⅱδ，CaMKⅡδ）在有氧运动调控自发性高血压大鼠心肌细胞凋亡中的作用。 方法：雄性12周龄自发性高血压大鼠和Wistar-Kyoto大鼠，随机分为正常安静组（WKY-SED）、正常有氧运动组（WKY-EX）、高血压安静组（SHR-SED）、高血压有氧运动组（SHR-EX）。经12周中等强度跑台运动（坡度0°，20m/min，60min/d，5d/w）后，测定大鼠尾动脉血压；Millar压力-容积系统测定在体心功能；Masson染色分析心肌胶原容积分数（CVF%）；caspase 3活性检测与TUNEL染色观察心肌细胞凋亡；Western Blot检测CaMKⅡδ、ox-CaMKⅡδ、IκBα、NF-κB P65、HSP70、Bax、Bcl-2的蛋白表达。 结果：12周有氧运动后，SHR-EX组较SHR-SED组心率、血压显著降低（P<0.05），心功能左室压力最大上升速率（+dp/dtmax）、射血分数（EF）与收缩末期压力-容积关系曲线（ESPVR）斜率（Ees）显著升高（P<0.05），心室压力最大下降速率（-dp/dtmax）的绝对值与每搏输出量（SV）显著升高（P<0.01），收缩末期压力（ESP）、舒张末期压力（EDP）与有效动脉弹性（Ea）显著下降（P<0.01），等容舒张常数（Tau）显著降低（P<0.05）。Masson染色结果显示SHR-EX组心肌组织纤维化减少，CVF %显著降低（P<0.01）。WKY-EX组较WKY-SED组caspase 3显著下降（P<0.05）。SHR-EX组较SHR-SED组caspase 3显著降低（P<0.05），TUNEL阳性颗粒数量显著降低（P<0.01）。Western Blot结果显示WKY-EX组较WKY-SED组NF-κB P65与Bax的蛋白表达、Bax/Bcl-2比值显著下降（P<0.05），IκBα与HSP70蛋白表达显著升高（P<0.01），Bcl-2蛋白表达显著上升（P<0.05）；SHR-EX组较SHR-SED组ox-CaMKⅡδ、NF-κB P65与Bax蛋白表达显著降低（P<0.05），Bax/Bcl-2比值显著降低（P<0.01），IκBα与Bcl-2蛋白表达显著上升（P<0.05），HSP70蛋白表达显著升高（P<0.01）。 结论：有氧运动通过下调SHR心肌ox-CaMKⅡδ抑制心肌细胞凋亡，同时激活抗凋亡相关信号通路改善心功能，可能是运动诱导高血压心脏重塑的机制之一。

Abstract:

      Abstract Objective： To explore the role of calcium/calmodulin-dependent protein kinase Ⅱ δ （CaMKⅡδ） in the regulation of cardiomyocyte apoptosis in spontaneous hypertensive rat （SHR） by aerobic exercise. Method： 12-week-old male SHR and WKY rats were randomly divided into normal control group （WKY-SED）， normal aerobic exercise group （WKY-EX）， hypertensive control group （SHR-SED） and hypertensive aerobic exercise group （SHR-EX）. After 12 weeks of treadmill running （slope 0°， 20m/min， 60min/d， 5d/w）， the blood pressure of the tail artery was measured. The Millar pressure-volume system was used to measure the heart function of the rats in vivo. Analysis of myocardial collagen volume fraction was made by Masson staining. Detection of caspase 3 activity and TUNEL staining were used to observe the apoptosis of cardiac myocytes. Western Blot was used to measure the protein expression of CaMKⅡδ， ox-CaMKⅡδ， IκBα， NF-κB P65， HSP70， Bax and Bcl-2 in rat myocardial tissue. Result： After 12 weeks of aerobic exercise， the heart rate and blood pressure in the SHR-EX group were significantly lower than those in the SHR-SED group （P<0.05）. Compared with the SHR-SED group， the maximum rising rate of left ventricular pressure（+dp/dtmax）， ejection fraction （EF） and slope Ees of end-systolic pressure-volume relationship curve（ESPVR） in the SHR-EX group were significantly increased （P<0.05）， and the absolute value of the maximum decreasing rate of ventricular pressure（-dp/dtmax） and stroke volume （SV） were significantly increased （P<0.01）； ventricular end-systolic pressure （ESP）， end-diastolic pressure （EDP） and effective arterial elasticity （Ea） were significantly decreased （P<0.01）； isovolumic diastolic constant （Tau） was significantly reduced （P<0.05）. Compared with the SHR-SED group， the myocardial tissue fibrosis in the SHR-EX group was reduced， and the CVF% decreased significantly （P<0.01）. Compared with WKY-SED group， the number of myocardial caspase 3 in WKY-EX group decreased significantly （P<0.05）. Compared with the SHR-SED group， the number of myocardial caspase 3 in the SHR-EX group was significantly reduced （P<0.05）， and the number of TUNEL-positive particles was significantly reduced （P<0.01）. The results of Western Blot showed that the expressions of NF-κB P65 and Bax protein and the ratio of Bax/Bcl-2 in the WKY-EX group were significantly lower than those in the WKY-SED group （P<0.05）， while the expressions of IκBα and HSP70 protein were significantly increased （P<0.01）. The expression of Bcl-2 protein increased significantly （P<0.05）. Compared with the SHR-SED group， the expressions of ox-CaMKIIδ， NF-κB P65 and Bax protein in the SHR-EX group were significantly decreased （P<0.05）. The ratio of Bax/Bcl-2 was significantly decreased （P<0.01）. The expressions of IκBα and Bcl-2 protein were significantly increased （P<0.05）， and the expression of HSP70 protein was significantly increased （P<0.01）. Conclusion： Aerobic exercise inhibits cardiomyocyte apoptosis by down-regulating SHR myocardium ox-CaMKⅡδ， while activating anti-apoptosis-related signal pathways， thus improves cardiac function， which may be one of the mechanisms of exercise-induced heart remodeling in hypertension.