Gu X H, Casley D J, Nayler W G
Department of Medicine, University of Melbourne, Victoria, Australia.
J Cardiovasc Pharmacol. 1989;13 Suppl 5:S171-3. doi: 10.1097/00005344-198900135-00046.
Standard binding and displacement techniques were used to identify high-affinity binding sites for [125I]-labeled endothelin-1 (ET-1) in membranes harvested from the hearts of adult female Sprague-Dawley rats. A single population of binding sites was identified, with a KD of 0.20 +/- 0.03 nM at 37 degrees C, and a Bmax of 93.5 +/- 6.4 fmol/mg protein. Bound [125I]ET-1 was displaced by ET-1 (10(-13)-10(-8) M), with a Ki of 0.08 nM. Neither (-)Bay K 8644 (10(-11)-10(-5) M), prenylamine (10(-11)-10(-5) M), (+)-cis-diltiazem (10(-10)-10(-5) M), (-)D888 (10(-10)-10(-5) M), nicardipine (10(-10)-10(-5) M), lidoflazine (10(-11)-10(-5) M), flunarizine (10(-11)-10(-5) M), omega-conotoxin (10(-13)-10(-7) M), nor prazosin (10(-10)-10(-5) M) displaced the bound ligand. Binding occurred in the absence of Ca2+ and was absent in heat-denatured membranes. These results are interpreted to mean that [125I]ET-1 binds to a single class of high-affinity binding sites that differ from those occupied by known regulators of voltage activated L- and N-type Ca2+ channels.
采用标准结合和置换技术，在成年雌性Sprague-Dawley大鼠心脏采集的膜中鉴定[125I]标记的内皮素-1（ET-1）的高亲和力结合位点。鉴定出单一的结合位点群体，在37℃时KD为0.20±0.03 nM，Bmax为93.5±6.4 fmol/mg蛋白质。结合的[125I]ET-1被ET-1（10-13 - 10-8 M）置换，Ki为0.08 nM。（-）Bay K 8644（10-11 - 10-5 M）、普尼拉明（10-11 - 10-5 M）、（+）-顺式地尔硫䓬（10-10 - 10-5 M）、（-）D888（10-10 - 10-5 M）、尼卡地平（10-10 - 10-5 M）、利多氟嗪（10-11 - 10-5 M）、氟桂利嗪（10-11 - 10-5 M）、ω-芋螺毒素（10-13 - 10-7 M）、去甲哌唑嗪（10-10 - 10-5 M）均不能置换结合的配体。结合在无Ca2+时发生，且在热变性膜中不存在。这些结果被解释为意味着[125I]ET-1与一类单一的高亲和力结合位点结合，这些位点不同于已知的电压激活L型和N型Ca2+通道调节剂所占据的位点。
