Boles R G, Yamamura H I, Schoemaker H, Roeske W R
J Pharmacol Exp Ther. 1984 May;229(2):333-9.
Binding of the dihydropyridine calcium channel antagonist [3H]nitrendipine to an intact rat brain mitochondrial-synaptosomal fraction (P2) was specific, saturable, temperature-dependent and of high affinity (Kd = 115-467 pM). The effects of the calcium channel antagonists verapamil and diltiazem on [3H]nitrendipine binding and their temperature dependence were investigated. At 0 and 25 degrees C, verapamil inhibited [3H]nitrendipine binding incompletely in a manner consistent with an allosteric modulation and nearly independent of the incubation temperature. The effects of diltiazem, however, were found to be highly temperature-dependent. At 25 and 37 degrees C, 10 microM diltiazem enhanced [3H]nitrendipine binding to values of 140 and 200% of control, respectively. At 0 degrees C, 10 microM diltiazem inhibited [3H]nitrendipine binding to a value of 68% of control. Analysis of saturation isotherms at steady state demonstrated that at all temperatures studied the effects of verapamil and diltiazem on [3H]nitrendipine binding were due to alterations in the ligand dissociation constant (Kd). At 25 degrees C, these alterations were mediated by changes in the rate of ligand-receptor complex dissociation. Competition studies of verapamil and diltiazem at 25 and 0 degrees C indicate that the effects of these two drugs on [3H]nitrendipine binding are mutually exclusive. We conclude that the binding of [3H]nitrendipine is allosterically modulated by spacially related binding sites for verapamil and diltiazem.
二氢吡啶类钙通道拮抗剂[3H]尼群地平与完整大鼠脑线粒体 - 突触体组分（P2）的结合具有特异性、饱和性、温度依赖性且亲和力高（Kd = 115 - 467 pM）。研究了钙通道拮抗剂维拉帕米和地尔硫䓬对[3H]尼群地平结合的影响及其温度依赖性。在0和25℃时，维拉帕米以与变构调节一致且几乎与孵育温度无关的方式不完全抑制[3H]尼群地平的结合。然而，发现地尔硫䓬的作用高度依赖于温度。在25和37℃时，10μM地尔硫䓬分别将[3H]尼群地平的结合增强至对照值的140％和200％。在0℃时，10μM地尔硫䓬将[3H]尼群地平的结合抑制至对照值的68％。稳态饱和等温线分析表明，在所研究的所有温度下，维拉帕米和地尔硫䓬对[3H]尼群地平结合的影响是由于配体解离常数（Kd）的改变。在25℃时，这些改变是由配体 - 受体复合物解离速率的变化介导的。维拉帕米和地尔硫䓬在25和0℃的竞争研究表明，这两种药物对[3H]尼群地平结合的影响是相互排斥的。我们得出结论，[3H]尼群地平的结合受到维拉帕米和地尔硫䓬空间相关结合位点的变构调节。
