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目的 观察不同剂量美托洛尔(Meto)对心力衰竭大鼠心肌连接蛋白43 (Cx43)表达及分布的影响,探讨其心脏保护机制.方法 SD大鼠100只随机(随机数字法)分为5组,每组20只:(1)假手术组(sham组);(2)心力衰竭模型组(HF组);(3) Meto治疗小剂量组[Meto A组,1.25mg/(k·d)];(4) Meto治疗中剂量组[Meto B组,5 mg/ (kg· d)]; (5)Meto治疗大剂量组[Meto C,20mg/ (kg·d)].缩窄大鼠腹主动脉建立心衰模型,术后第4周开始给药至第8周,术后第8周取材免疫组化观察大鼠心肌Cx43表达量及分布模式,Western blot检测心肌总Cx43 (T-Cx43)、磷酸化Cx43 (P-Cx43)表达水平.结果 (1) HF组大鼠与Sham组比较,心脏T-Cx43分布紊乱明显,Cx43mRNA表达及P-Cx43、T-Cx43蛋白表达显著增加;MetoC组虽较Meto A、MetoB组进一步显著改善HF大鼠心脏T-Cx43分布紊乱情况,但显著抑制HF大鼠心脏T-Cx43表达(P＜0.01);Meto A、MetoB组未显著抑制HF大鼠心脏T-Cx43蛋白的表达.(2)HF组大鼠中P-Cx43表达量显著高于sham组(P＜0.叭),随Meto治疗剂量的逐级增加各治疗组P-Cx43表达量较HF组逐级降低(MetoAvs.HF,P＜0.05;MetoBvs.HF,P＜0.01;MetoCvs.HF,P＜0.01),且Meto治疗组各组间比较差异具有统计学意义(P＜0.01).结论 Meto可通过抑制心肌Cx43磷酸化及改善其分布紊乱而发挥心脏保护作用.“,”Objective To observe the effects of metoprolol (Meto) in different doses on myocardial connexin43 (Cx43) expression and distribution pattern in heart failure rats with chronic heart failure,so as to explore its cardiac protection mechanism.Methods One hundred Sprague-Dawley rats were randomly (random number) divided into 5 groups (n =20 in each group):(1) sham group; (2) heart failure group (HF group) ; (3) low-dose metoprolol treated group [MetoA group,1.25 mg/ (kg · d)] ; (4) mediumdose metoprolol treated group [MetoB group,5 mg/ (kg · d)] ; (5) large-dose metoprolol treated group [MetoC group,20 mg/ (kg · d)].Rats of HF group and metoprolol treated group were subjected to abdominal aortic ligation,and different doses of metoprolol were given 4 weeks after ligation till 8 weeks.The rats were sacrificed 8 weeks after operation,and the myocardial Cx43 expression and distribution patterns were observed by using immunohistochemistry,and total Cx43 (T-Cx43)、Phospho-Cx43 (P-Cx43) protein levels were detected by Western blotting.Results (1) In HF group,rat heart had obvious T-Cx43 disordered distribution with significant increase in Cx43 P-Cx43,T-Cx43 protein expression compared with Sham group; whereas medium-dose and low-dose Meto treatment did not significantly inhibit the T-Cx43 protein expression of HF rat heart,and large-dose Meto therapy could improve disordered T-Cx43 distribution and inhibit T-Cx43 protein expression of HF rat heart (P ＜ 0.01).(2) Western blot showed P-Cx43 expression was significantly higher in the HF group than that in the sham group (P ＜ 0.01),and in all metoprolol treated groups,P-Cx43 expressions were significantly decreased compared with the HF group (MetoAvs.HF,P ＜0.05; MetoB vs.HF,P ＜0.01; MetoC vs.HF,P＜0.01),and pairwise comparisons among the metoprolol treated groups also showed significant differences (P ＜ 0.01).ConclusionsMeto could exert a cardiac protective effect by inhibiting myocardial Cx43 phosphorylation and ameliorate its distribution disorder.