Rattigan S, Appleby G J, Edwards S J, McKinstry W J, Colquhoun E Q, Clark M G, Richter E A
Biochem Biophys Res Commun. 1986 May 14;136(3):1071-7. doi: 10.1016/0006-291x(86)90442-0.
Sarcolemma-enriched preparations from muscles rich in slow oxidative red fibres contained specific binding sites for the alpha 1 antagonist, prazosin (e.g. soleus Kd 0.13 nM, Bmax 29 fmol/mg protein). Binding sites for prazosin were almost absent from white muscle. Displacement of prazosin binding from sarcolemma of soleus muscle (phentolamine greater than phenylephrine greater than idazoxan greater than yohimbine) suggested that the receptors were alpha 1. Binding sites for dihydroalprenolol (beta antagonist) were also more concentrated on red than white muscle and outnumbered prazosin sites by approx. 10:1. Binding sites for idazoxan (alpha 2 antagonist) were undetectable. Contamination of sarcolemma-enriched preparations by endothelial tissue indicated by the activity of angiotensin converting enzyme did not correlate with prazosin binding. It is concluded that post-synaptic alpha 1 adrenergic receptors are present on the sarcolemma of slow oxidative red fibres of rat skeletal muscle. The presence provides the mechanistic basis for apparent alpha-adrenergic effects to increase glucose and oxygen uptake in perfused rat hindquarter.
富含慢氧化型红色纤维的肌肉中富含肌膜的制剂含有α1拮抗剂哌唑嗪的特异性结合位点（例如比目鱼肌Kd为0.13 nM，Bmax为29 fmol/mg蛋白质）。白色肌肉中几乎没有哌唑嗪的结合位点。比目鱼肌肌膜上哌唑嗪结合的置换情况（酚妥拉明＞去氧肾上腺素＞咪唑克生＞育亨宾）表明这些受体是α1。二氢阿普洛尔（β拮抗剂）的结合位点在红色肌肉中也比白色肌肉中更集中，且数量比哌唑嗪位点多约10:1。未检测到咪唑克生（α2拮抗剂）的结合位点。血管紧张素转换酶活性表明富含肌膜的制剂被内皮组织污染的情况与哌唑嗪结合无关。结论是大鼠骨骼肌慢氧化型红色纤维的肌膜上存在突触后α1肾上腺素能受体。这一存在为灌注大鼠后肢中明显的α肾上腺素能效应增加葡萄糖和氧气摄取提供了机制基础。
