Marangos P J, Patel J, Miller C, Martino A M
Life Sci. 1982 Oct 11;31(15):1575-85. doi: 10.1016/0024-3205(82)90049-2.
The binding of the calcium antagonist [3H] nitrendipine ([3H] NDP) to brain and heart is described and the brain site is characterized. The binding is saturable, specific and of very high affinity with KD values of 0.16 nM in brain and 0.21 nM in heart. Our kinetic results are similar to those recently reported by two other groups (1, 2), indicating a saturable, high affinity binding site in brain. In brain the binding sites are enriched in crude nuclear and synaptosomal fractions. The highest levels of binding are seen in the hippocampus, caudate and cerebral cortex with much lower levels in the cerebellum and pons. Calcium has a marked stimulatory effect on [3H] NDP binding at 10(-4) M. Addition of 0.5 mM CaCl2 to EDTA treated membranes nearly doubles the number of binding sites. Of the many drugs and neurotransmitters tested only other calcium antagonists, i.e. verapamil, inhibit binding (IC50 = 250 nM). The inhibition of [3H] NDP binding by verapamil is apparently non-competitive and not complete, suggesting that [3H] NDP binds to several sites, only some of which are inhibited by verapamil. The [3H] NDP binding site is probably a protein since it is very sensitive to trypsin, heat and sulfhydryl reagents.
描述了钙拮抗剂[3H]尼群地平（[3H] NDP）与脑和心脏的结合情况，并对脑内结合位点进行了表征。这种结合具有饱和性、特异性且亲和力极高，在脑中的KD值为0.16 nM，在心脏中为0.21 nM。我们的动力学结果与其他两个研究小组最近报道的结果相似（1, 2），表明脑中存在一个饱和的、高亲和力的结合位点。在脑中，结合位点在粗核和突触体组分中富集。在海马体、尾状核和大脑皮层中观察到最高水平的结合，而在小脑和脑桥中的水平则低得多。钙在10^(-4) M时对[3H] NDP结合有显著的刺激作用。向经EDTA处理的膜中添加0.5 mM CaCl2，结合位点数量几乎增加一倍。在测试的众多药物和神经递质中，只有其他钙拮抗剂，即维拉帕米，能抑制结合（IC50 = 250 nM）。维拉帕米对[3H] NDP结合的抑制显然是非竞争性的且不完全，这表明[3H] NDP与多个位点结合，其中只有一些位点被维拉帕米抑制。[3H] NDP结合位点可能是一种蛋白质，因为它对胰蛋白酶、热和巯基试剂非常敏感。
