Castro E, Oset-Gasque M J, Cañadas S, Gimenez G, González M P
Instituto de Bioquímica (Centro mixto C.S.I.C.-U.C.M.), Facultad de Farmacia, Madrid, Spain.
J Neurosci Res. 1988;20(2):241-5. doi: 10.1002/jnr.490200213.
The effect of several ligands and Ca2+ ions on [3H]GABA binding to bovine adrenal medulla membranes was investigated. Without any blockade, the [3H]GABA binding showed two components, one of low affinity (Kd = 139 +/- 22 nM and Bmax = 3.2 +/- 0.4 pmol/mg protein) and the other of high affinity (Kd = 41 +/- 6 nM and Bmax = 0.35 +/- 0.26 pmol/mg protein). Muscimol specifically blocked low-affinity sites, and (-)baclofen blocked high-affinity components. Ca2+ ions were strictly necessary for maximum binding to high-affinity sites, whereas they did not significantly affect sites of the lower affinity. These results show that the bovine adrenal medulla has a GABAA receptor population of low affinity together with a GABAB receptor of high affinity.
研究了几种配体和钙离子对[³H]γ-氨基丁酸（GABA）与牛肾上腺髓质膜结合的影响。在没有任何阻断剂的情况下，[³H]GABA结合呈现出两个组分，一个是低亲和力组分（解离常数Kd = 139±22 nM，最大结合量Bmax = 3.2±0.4 pmol/mg蛋白质），另一个是高亲和力组分（Kd = 41±6 nM，Bmax = 0.35±0.26 pmol/mg蛋白质）。蝇蕈醇特异性阻断低亲和力位点，而（-）巴氯芬阻断高亲和力组分。钙离子对于与高亲和力位点的最大结合是绝对必要的，而它们对低亲和力位点没有显著影响。这些结果表明，牛肾上腺髓质具有低亲和力的GABAA受体群体以及高亲和力的GABAB受体。
