Alteration of cardiac M3 receptor and its relationship with arrhythmias in drug-induced and ischemia-induced arrhythmic models

AIM: To investigate the alteration of cardiac M₃ receptor and its relationship with arrhythmias in various arrhythmic models. METHODS: Forty Wistar rats were randomly divided into 4 groups: control, aconitine, BaCl₂ and ischemia. In the later three groups, arrhythmias were induced by treatment with aconitine, BaCl₂ and coronary artery occlusion, respectively. The arrhythmias were recorded for 1 h. Western blotting was then used to detect M₃ receptor contents. RESULTS: Arrhythmias were all induced in each group. In aconitine-induced arrhythmias, duration of arrhythmias and arrhythmia score were significantly increased than those in other two model groups. Western blotting showed that the expression of M₃ receptor upregulated 2.3, 1.4 and 1.3 folds respectively, more abundant in various arrhythmic groups than that in the normal control. Moreover, M3 receptor expression in aconitine group increased significantly than that in BaCl₂ and ischemia group. The arrhythmias and M₃ receptor protein expressions in myocytes were positively correlated. CONCLUSION: Arrhythmias upregulate the expression of cardiac M₃ receptor. The upregulating levels of M₃ receptor proteins diverge strikingly in different arrhythmic models. It is probably that the diversity of increase in M₃ receptor is positive related to severity of ventricular arrhythmias.