目的研究美托洛尔下调CaMKⅡδC-p38通路对异丙肾上腺素诱导心力衰竭的保护机制。方法40只SD大鼠随机分成四组,正常对照组(Control)、异丙肾上腺组(Iso)、异丙肾上腺+美托洛尔组(Iso+Meto)和美托洛尔组(Meto),每组10只,所有动物均自由进食进水。(1)Iso组大鼠背部皮下注射Iso 5 mg/(kg·d),连续10 d;对照组背部皮下注射相同体积的生理盐水;Iso+Meto组大鼠背部皮下注射Iso 5 mg/(kg·d),连续10 d,在背部皮下注射Iso前1天开始Meto 10 mg/(kg·d)灌胃,连续4周;Meto组给予10 mg/(kg·d),连续4周灌胃;(2)所有大鼠饲养4周后,采用Millar P-V Loop导管经颈动脉插管至左心室,使用Powerlab生理记录系统测量血流动力学相关指标;统计各组大鼠心脏重量和心脏重量/体重比值;(3)TUNEL法和Caspase-3活性检测心肌细胞凋亡;(4)ELISA分析CAMKⅡ活性;(5)Western blot检测CaMKⅡδ、p-CaMKⅡδ、CaMKⅡδC和MAPKs家族(p-38、JNK、ERK)、和凋亡相关基因Bcl-2/Bax的蛋白表达水平。结果40只SD大鼠实验过程精神状态好,进食进水正常,无呼吸困难及水肿。(1)Iso和Meto干预SD大鼠心脏重塑和血流动力学指标有显著改变,与Control组相比,Iso组心脏重量和心脏重量指数明显增加(P<0.05);而Iso+Meto组心脏重量和心脏重量指数明显低于Iso组(P<0.05);大鼠体重、肝重和肺重四组间也无明显差异。大鼠血流动力学指标心率(HR)、平均动脉血压(MBP)和左室舒张末压(LVEDP)Iso组明显高于Control组;但左室压力变化速率(LV±dp/dt max) Iso组明显低于Control组(P<0.05);而Iso+Meto组HR、MBP和LVEDP明显低于Iso组(P<0.05),但Iso+Meto组±dp/dtmax明显高于Iso组(P<0.05);(2)Iso组SD大鼠心肌细胞TUNEL阳性细胞数和Caspase-3活性明显高于Control组(P<0.05);Western杂交分析检测Iso组抗凋亡蛋白bcl-2表达明显低于Control组(P<0.05),而促抗凋亡蛋白Bax表达明显高于Control组;(3)CaMKⅡ活性分析结果显示Iso组明显高于Control组(P<0.05)。说明Iso诱导了明显的心肌细胞凋亡,并且心肌细胞凋亡和CaMKⅡ活性明显正相关;(4)CaMKⅡδ异构体、MAPKs家族在β1-AR持久兴奋的SD大鼠心肌表达情况,我们用Western blot方法分析结果显示Iso组CaMKⅡδC和p-CaMKⅡδ、p38 MAPK、JNK蛋白表达明显高于Control组(P<0.05),但与Control组比较,Iso组ERK蛋白表达明显减少(P<0.05)。与Iso组相比,β1-AR阻滞剂Meto可减少CaMKⅡδC和p-CaMKⅡδ、p38 MAPK、JNK蛋白表达,增加ERK蛋白表达(P<0.05)。结论(1)持久兴奋β1-AR激活CaMKⅡδC-p38通路诱导心肌细胞凋亡,导致心肌重塑、心力衰竭;(2)β1-AR阻断剂美托洛尔可阻断β1-AR持久激活CaMKⅡδC—p38导致心肌细胞凋亡途径,对心脏有保护效应。 Objective To investigate the protective mechanism of metoprolol down-regulating CaMKⅡδC-p38 pathway on isoproterenol-induced heart failure. Methods Forty Sprague-Dawley rats were randomly divided into four groups: control group, Iso group, Iso + Meto group and metoprolol group (Meto) Group of 10, all animals are free to eat water. (1) Iso group was injected subcutaneously with Iso 5 mg / (kg · d) on the back of the rats for 10 days. The control group was injected subcutaneously with the same volume of saline. · D) for 10 days, Meto 10 mg / (kg · d) was given intragastrically on the 1st day before the back of subcutaneous injection for 4 consecutive weeks; Meto group was given 10 mg / (kg · d) ; (2) After 4 weeks, all rats were cannulated with a Millar PV Loop through the carotid artery to the left ventricle, and the Powerlab physiological recording system was used to measure the hemodynamic parameters. The heart weight and heart weight / (3) TUNEL assay and Caspase-3 activity were used to detect cardiomyocyte apoptosis; (4) ELISA was used to analyze the activity of CAMKⅡ; (5) Western blot was used to detect the expression of CaMKⅡδ, p-CaMKⅡδ, CaMKⅡδC and MAPKs family (p38, JNK, ERK), and apoptosis related gene Bcl-2 / Bax protein expression levels. Results Forty Sprague-Dawley rats were in good mental state during the experimental period, with normal infants’ intake and no dyspnea and edema. (1) Compared with Control group, Iso and Meto significantly increased heart remodeling and hemodynamic parameters in SD rats (P <0.05), while those in Iso + Meto group Heart weight and heart weight index were significantly lower than the Iso group (P <0.05); body weight, liver weight and lung weight were no significant differences between the four groups. The indexes of hemodynamics, heart rate (HR), mean arterial blood pressure (MBP) and left ventricular end-diastolic pressure (LVEDP) in the Iso group were significantly higher than those in the Control group. However, the LV ± dp / dt max (P <0.05). However, HR, MBP and LVEDP in Iso + Meto group were significantly lower than those in Iso group (P <0.05), but ± dp / dtmax in Iso + Meto group was significantly higher than that in Iso group 0.05). (2) The TUNEL-positive cells and Caspase-3 activity of cardiomyocytes in Iso group were significantly higher than those in Control group (P <0.05). The expression of anti-apoptotic protein bcl-2 in Iso group was significantly lower than that of Iso group Control group (P <0.05), while the expression of anti-apoptotic protein Bax was significantly higher than that of Control group. (3) CaMKⅡactivity assay showed that Iso group was significantly higher than Control group (P <0.05). Iso-induced cardiomyocyte apoptosis, and myocardial cell apoptosis and CaMKII activity was significantly positively correlated; (4) CaMKⅡδ isoform, MAPKs family in β1-AR sustained and excited SD rat myocardial expression, we used Western The results of blot analysis showed that the expressions of CaMKⅡδC and p-CaMKⅡδ, p38 MAPK and JNK in Iso group were significantly higher than those in Control group (P <0.05). Compared with Control group, the expression of ERK protein in Iso group was significantly decreased (P <0.05). Compared with the Iso group, the β1-AR blocker Meto reduced the expression of CaMKⅡδC and p-CaMKⅡδ, p38 MAPK and JNK protein and increased the expression of ERK protein (P <0.05). (2) β1-AR blocker metoprolol can block β1-AR lasting activation of CaMKⅡδC -p38 lead to myocardial cell apoptosis pathway, have a protective effect on the heart.