Kim Y S, Sainz R D
University of Hawaii, Manoa 96822.
Life Sci. 1992;50(6):397-407. doi: 10.1016/0024-3205(92)90374-x.
Chronic administration of some beta-adrenergic agonists markedly stimulates hypertrophy of skeletal muscles. It appears that type II fibers are more responsive to beta-adrenergic agonists than type I fibers. The hypertrophic effect of beta-adrenergic agonists is transient, with the effect diminishing during prolonged treatment. Similarly, some cellular responses including the increase in RNA concentration and the decrease in calpain I activity are also short-lived. Recent evidence suggests that the temporal response is associated with decreased beta-adrenoceptor density. Both increased rate of protein synthesis and/or decreased protein degradation have been suggested as the mechanism of action of these compounds on hypertrophy of skeletal muscles. It is important to consider the temporal nature of cellular responses to chronic treatment of beta-adrenergic agonists as well as the differential effects of these compounds on protein metabolism among skeletal muscle fiber types when investigating the mechanism(s) of action of these compounds.
长期施用某些β-肾上腺素能激动剂可显著刺激骨骼肌肥大。似乎II型纤维比I型纤维对β-肾上腺素能激动剂更敏感。β-肾上腺素能激动剂的肥大效应是短暂的，在长期治疗过程中效应会减弱。同样，一些细胞反应，包括RNA浓度的增加和钙蛋白酶I活性的降低，也是短暂的。最近的证据表明，这种时间反应与β-肾上腺素能受体密度降低有关。蛋白质合成速率增加和/或蛋白质降解减少都被认为是这些化合物对骨骼肌肥大作用的机制。在研究这些化合物的作用机制时，重要的是要考虑细胞对β-肾上腺素能激动剂长期治疗的时间反应特性，以及这些化合物对不同类型骨骼肌纤维蛋白质代谢的差异影响。
