美托洛尔对大鼠急性心肌梗死后交感神经重构的抑制作用

The Inhibitory Effect of Metoprolol on Sympathetic Nerve Remodeling after Acute Myocardial Infarction in Rats

目的探讨大鼠心肌梗死后交感神经重构现象以及美托洛尔对重构的抑制作用。方法心肌梗死模型成功后的48只大鼠随机分为心肌梗死组(A组)和美托洛尔治疗组[B组,10mg/(kg.d)]。各组分别在3个不同的时间点(3d、7d、30d)进行观测。各时间点配以相同只数的大鼠,只穿线不结扎作为对照组。测定大鼠心电图,并计算QT离散度(QTd)。连续记录大鼠心电图,并对心律失常进行评分。用免疫组化的方法检测各组大鼠心肌梗死周边区交感神经密度。结果A组7d、30d时心肌梗死周围区交感神经密度与对照组比有明显增加(P<0.05)。B组在第30天时,梗死周边区交感神经支配密度要明显低于同时间点的A组(P<0.05)。美托洛尔治疗后各时间点QTd和心律失常评分均比相应A组显著降低(P<0.05)。结论美托洛尔能抑制心肌梗死后交感神经的重构,降低QTd和心律失常,第30天时,美托洛尔对降低心律失常的作用部分是通过抑制交感神经重构介导的。

Objective To investigate the inhibitory effect of metoprolol on sympathetic nerve remodeling after acute myocardial infarction in rats.Methods Forty eight Wistar rats underwent LAD occlusion operation were randomly divided to group myocardial infarction（group A）and group metoprolol therapy（group B,10 mg/kg·d）by gavage.Sham operation in rats were served as group control.QT dispersion（QTd）was calculated and the score of arrhythmia was determined.The density of sympathetic nerve in the peri-infarction zone was estimated by immunohistochemistry stain at 3 d,7 d and 30 d after operation.Results The density of sympathetic nerve increased significantly in group A at 7 d and 30 d comparing with group control.Metoprolol decreased the density of nerve fiber in peri-infarction zone in relative to group A.Metoprolol significantly decreased QTd and the arrhythmia score at every time-point（P〈0.05）.Conclusion Metoprolol inhibited the remodeling of sympathetic nerve fiber in peri-infarction zone after acute myocardial infarction and decreased QTd and arrhythmia.The effect was associated with inhibiting sympathetic nerve remodeling.