A unique regulatory profile and regional distribution of [3H]pirenzepine binding in the rat provide evidence for distinct M1 and M2 muscarinic receptor subtypes.
A unique regulatory profile and regional distribution of [3H]pirenzepine binding in the rat provide evidence for distinct M1 and M2 muscarinic receptor subtypes.
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大鼠中[3H]哌仑西平结合的独特调节特征和区域分布为不同的 M1 和 M2 毒蕈碱受体亚型提供了证据。
DOI：
10.1016/0024-3205(83)90652-5
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发表时间：
1983
期刊：
影响因子：
6.1
通讯作者：
Roeske,WR
中科院分区：
文献类型：
--
作者：
Watson,M;Yamamura,HI;Roeske,WR
我们最近证明，非经典的毒蕈碱受体拮抗剂[3 H]哌仑西平（[3 H]PZ）确定了一个高亲和力人口的毒蕈碱网站在大鼠大脑皮层。我们现在报告说，皮质毒蕈碱网站，[3 H]PZ与高亲和力的结合是由离子，但不是鸟嘌呤核苷酸调制。我们还研究了平衡[3 H]PZ结合各种大鼠组织匀浆中使用一种新的快速过滤试验。在10 mM磷酸钠钾缓冲液中，所有区域饱和等温线均产生相似的高亲和力解离常数（Kd= 2 − 8 nM）。受体密度（Bmaxin fmol/mg组织）变化如下：纹状体= 154.5，大脑皮层= 94.6，海马= 94.3，回肠= 1.3，小脑= 1.0，心脏= 0.45。大脑皮层和海马具有61%的纹状体结合位点，而回肠、小脑和心脏分别仅含有0.84%、0.65%和0.29%的纹状体结合位点。心脏、回肠和小脑中的[3 H]PZ位点分别占使用[3 H]（-）奎宁环基二苯乙酸酯获得的位点的3.1%、9.6%和10.4%。因此，[3 H]PZ标记高亲和力毒蕈碱受体结合位点，其组织分布与不同M1和M2受体亚型的概念相容。因此，心脏、小脑和回肠等区域将被称为M2，尽管每个区域都有极少量的M1高亲和力[3 H]PZ位点。因此，[3 H]PZ似乎是M1受体鉴定的有用配体。此外，无法证明鸟嘌呤核苷酸对高亲和力[3 H]PZ与推定的M1受体结合的显著影响，这表明M1位点可能不依赖于鸟嘌呤调节蛋白。
We recently demonstrated that the non-classical muscarinic receptor antagonist [3H]pirenzepine ([3H]PZ) identifies a high affinity population of muscarinic sites in the rat cerebral cortex. We now report that cortical muscarinic sites to which [3H]PZ binds with high affinity are modulated by ions but not guanine nucleotides. We also have examined equilibrium [3H]PZ binding in homogenates of various rat tissues using a new rapid filtration assay. All regional saturation isotherms yielded a similar high affinity dissociation constant (Kd= 2 − 8 nM) in 10 mM sodium-potassium phosphate buffer. Receptor density (Bmaxin fmol/mg tissue) varied as follows: corpus striatum = 154.5, cerebral cortex = 94.6, hippocampus = 94.3, ileum = 1.3, cerebellum = 1.0, and heart = 0.45. The cerebral cortex and hippocampus possess 61 percent of striatal binding sites, while the ileum, cerebellum and heart contain only 0.84 percent, 0.65 percent and 0.29 percent of striatal sites respectively. The [3H]PZ sites in heart, ileum, and cerebellum represent 3.1 percent, 9.6 percent, and 10.4 percent of the sites obtained by using [3H](−)quinuclidinyl benzilate. Thus, [3H]PZ labels high affinity muscarinic receptor binding sites with a tissue distribution compatible with the concept of distinct M1and M2receptor subtypes. Accordingly, regions such as heart, cerebellum, and ileum would be termed M2, though each have an extremely small population of the M1high affinity [3H]PZ site. [3H]PZ therefore appears to be a useful ligand for M1receptor identification. Furthermore, the inability to demonstrate a significant effect of guanine nucleotides upon high affinity [3H]PZ binding to putative M1receptors suggests that M1sites may be independent of a guanine regulatory protein.