Nylander E
Acta Physiol Scand. 1981 Aug;112(4):449-54. doi: 10.1111/j.1748-1716.1981.tb06843.x.
Metoprolol-treated and untreated rats were subjected to the same treadmill running program for 12 weeks. After training and withdrawal of metoprolol, the treated rats had a more pronounced bradycardia during submaximal exercise than non-treated rats, although they had a lower heart weight/body weight ratio. The intrinsic heart rate (IHR) was slightly but not significantly lower in trained than in untrained untreated animals. The IHR was not altered by a period of metoprolol treatment neither alone nor in combination with training. It is concluded that chronic cardioselective beta-blockade during training augments the training-induced bradycardia but may impair the development of cardiac hypertrophy. The training-induced bradycardia is thus not related to the degree of heart rate increase during exercise for its development.
美托洛尔治疗组和未治疗组大鼠接受相同的跑步机跑步程序，为期12周。在训练并停用美托洛尔后，治疗组大鼠在次最大运动期间的心动过缓比未治疗组大鼠更明显，尽管它们的心脏重量/体重比更低。训练组大鼠的固有心率（IHR）略低于未训练的未治疗动物，但差异不显著。美托洛尔治疗一段时间，无论是单独治疗还是与训练联合治疗，均未改变IHR。结论是，训练期间的慢性心脏选择性β受体阻滞剂可增强训练诱导的心动过缓，但可能损害心脏肥大的发展。因此，训练诱导的心动过缓与其发展过程中运动时心率增加的程度无关。
