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Objectives To investigate the effects of adrenergic receptor antagonist ( metoprolol or prazosin) on myocardial α1-AR density and the changes of ventricular effective refractory period dispersion (VERP-D) in rabbits after myocardial infarction.Methods twenty-four adult male New Zealand rabbits were divided into four groups at random: control group ( n = 6 ); MI with placebo group ( n = 6 ); MI with metoprolol group (n = 6 ) ; MI with prazosin group (n = 6 ). The rabbits received corresponding drugs for seven days, beginning at the first day after MI and myocardial α1-AR density were measured and meanwhile, myocardial β-AR was also measured.Results In the placebo group, the density of ventricular α1-AR was increased in comparison with control group ( α1 -AR in normal region 36.9 ± 0.2 vs 27.3 ±0.9 fmol mg-1 Pro-1 ,p ＜0.01; α1-AR in ischemic region 33.0±0.9 vs 26.6 ±0.4 fmol mg-1 pro-1 P ＜0.01). In the metoprolol group, it was also increased in comparison with control group( α1-AR in normal region 44.7 ±1.5 vs 27.3 ±0.9 fmol mg-1 pro-1 ,P ＜0.01; α1-AR in ischemic region 33.6 ± 0.5 vs 26.6 ± 0.4 fmol mg-1pro-1 , P ＜ 0.01 ). Meanwhile the density of ventricular α1-AR in normal region in the metoprolol group was increased in comparison with placebo group (44.7 ±1.5 vs 36.9 ±0.2 fmol mg-1 pro-1,P＜0.01). While it decreased in the prazosin group in comparison with control group ( α1-AR in normal region 22.5 ± 0.6 vs27.3 ±0.9 fmol mg-1pro-1 ,P ＜0.01; α1-AR in ischemic region 20.9 ±0.4 vs 26.6 ±0.4 fmol mg-1 pro-1,P ＜0.01 ). VERP-D was increased after MI(P ＜0.01 ).After treatment with metoprolol or prazosin, VERP-D was decreased ( P ＜ 0.01 ). Conclusions After acute MI, α1-AR of ventricular myocardium was upregulated, which may be accompanied by its activitation.The density of myocardial α1-AR became upregulated more dramatically treated with metoprolol and downregulated with prazosin. When treated with metoprolol or prazosin, VERP-D decreased.