Liggett S B, Shah S D, Cryer P E
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Am J Physiol. 1988 Jun;254(6 Pt 1):E795-8. doi: 10.1152/ajpendo.1988.254.6.E795.
Human skeletal muscle beta-adrenergic receptors were characterized by 125I-iodopindolol radioligand-binding studies of homogenates prepared from small muscle samples obtained by percutaneous needle biopsy from the gastrocnemius of six normal subjects. Binding was saturable, reversible, and stereospecific, with typical kinetics and a rank-order potency characteristic of a beta-adrenergic receptor. In saturation-binding studies, the receptor density was 9.7 +/- 1.9 fmol/mg protein, with a dissociation constant of 24 +/- 2.2 pM. Competition studies with selective antagonists revealed a population of receptors exclusively of the beta 2-subtype. Basal and isoproterenol-stimulated adenylate cyclase activities were 79 +/- 22 and 150 +/- 60 pmol adenosine 3',5'-cyclic monophosphate.min-1.mg protein-1, respectively. These results support pharmacological observations of beta-adrenergic receptor-mediated cellular responses in mammalian skeletal muscle. By use of these methods, small quantities of skeletal muscle obtained in this manner can be used to study in vivo beta-adrenergic receptor regulatory phenomena in humans.
通过对从6名正常受试者腓肠肌经皮穿刺活检获取的小块肌肉样本制备的匀浆进行¹²⁵I-碘吲哚洛尔放射性配体结合研究，对人骨骼肌β-肾上腺素能受体进行了表征。结合具有饱和性、可逆性和立体特异性，具有典型的动力学以及β-肾上腺素能受体的效价排序特征。在饱和结合研究中，受体密度为9.7±1.9 fmol/mg蛋白质，解离常数为24±2.2 pM。用选择性拮抗剂进行的竞争研究显示存在一群仅为β₂亚型的受体。基础和异丙肾上腺素刺激的腺苷酸环化酶活性分别为79±22和150±60 pmol腺苷3',5'-环磷酸每分钟每毫克蛋白质⁻¹。这些结果支持了对哺乳动物骨骼肌中β-肾上腺素能受体介导的细胞反应的药理学观察。通过使用这些方法，以这种方式获得的少量骨骼肌可用于研究人体体内β-肾上腺素能受体调节现象。
