Nerme V, Severne Y, Abrahamsson T, Vauquelin G
Biochem Pharmacol. 1985 Aug 15;34(16):2917-22. doi: 10.1016/0006-2952(85)90016-4.
The tight binding of noradrenaline (NA) to beta-adrenergic receptors was studied in membranes from the left ventricular myocardium of the rat. Addition of GTP (0.1 mM) to membrane preparations from control rats (NA concentration 8.5 +/- 2.1 nM) caused a 4-35% (N = 8) increase (P less than 0.01) in the number of specific binding sites of 125Ipindolol. In contrast, addition of GTP did not cause any changes in the number of beta-adrenergic receptors in heart membranes from reserpinized animals (NA concentration less than 0.1 nM). In heart membranes from reserpinized animals, preincubation with NA (followed by washing) revealed a time- and concentration-dependent decrease with a maximum of 35-40% in the 125Ipindolol-binding sites. This agonist-mediated decrease in the number of receptors was prevented if GTP was also present in the NA-preincubation medium. It is concluded that NA can undergo tight binding to beta-adrenergic receptors in rat heart membranes. The heart-membrane preparations contain endogenous NA which, via tight agonist binding, is responsible for masking part of the beta-adrenergic receptor population.
研究了去甲肾上腺素（NA）与大鼠左心室心肌膜中β-肾上腺素能受体的紧密结合情况。向对照大鼠的膜制剂（NA浓度8.5±2.1 nM）中添加GTP（0.1 mM），导致[125I]-吲哚洛尔特异性结合位点数量增加4 - 35%（N = 8）（P < 0.01）。相比之下，向利血平化动物的心脏膜中添加GTP，并未引起β-肾上腺素能受体数量的任何变化（NA浓度< 0.1 nM）。在利血平化动物的心脏膜中，用NA预孵育（随后洗涤）显示[125I]-吲哚洛尔结合位点呈时间和浓度依赖性减少，最大减少35 - 40%。如果在NA预孵育培养基中也存在GTP，则可防止这种激动剂介导的受体数量减少。结论是，NA可与大鼠心脏膜中的β-肾上腺素能受体发生紧密结合。心脏膜制剂中含有内源性NA，其通过紧密的激动剂结合，导致部分β-肾上腺素能受体群体被掩盖。
