The Effect Of Combined Metoprolol And Terbutalin Therapy On Cardiac Function In The Heart Failure Rats

Objective To observe the effect of combined metoprolol and terbutalin therapy on cardiac funct-ion in the heart failure rats and to investigate the possible mechanism.Methods The rat heart failure model was established by ligation of the left anterior descending of coronary arteries (LADs). The heart failure rats were randomly divided into a heart failure model group (saline,n=7), a heart failure plus metoprolol treatment group (metoprolol group;20mg/kg twice daily/gavage,n=7) and a heart failure plus combined treatment group (combined treatment group; terbutalin2mg/kg and metoprolol20mg/kg twice daily/gavage,n=8). An additional8rats underwent a sham operation (SH) without actual coronary ligation. Treatment was started2weeks after coronary ligation. After8weeks treatment, echocardiographic (Echo) assessment was conducted and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was used to evaluate cardiomyocyte apoptosis.Results (1) Compared with SH group, left ventricular end-diastolic dimention (LVEDd), left ventricular end-systolic dimention (LVESd) and E/A ratio were significantly increased and ejection fraction (EF), fractional shortening (FS) significantly reduced in heart failure group (P<0.01for all). Compared with the heart failure group, LVEDd and E/A ratio were significantly reduced (P<0.01), LVESd reduced (P<0.05), EF significantly increased (P<0.01) in metoprolol group, whereas FS did not differ. Compared with the heart failure group, LVEDd, LVESd, and E/A ratio were significantly reduced (P<0.01), EF and FS were significantly increased (P<0.01) in combined treatment group.Compared with metoprolol group, LVEDd and LVESd were reduced (P<0.01), EF and FS increased (P<0.01) in combined treatment group, whereas E/A ratio did not differ.(2) Myocardiol infarction (MI) size did not differ among the heart failure model groups.(3) Compared with SH group, myocardiol cell apoptosis index (AI) was significantly increased in the heart failure group(P<0.01). Compared with the heart failure group, AI was reduced in treatment groups. Compared with metoprolol group, AI was reduced in combined treatment group.Conclusion Terbutalin enhances the effect of metoprolol possibly by reducing cardiomyocyte apoptosis in the heart failure rats to improve cardiac function and prevent cardiac remodeling.