Fernando J C, Abdallah E A, Evinger M, Forray C, el-Fakahany E E
Department of Pharmacology and Toxicology, University of Maryland School of Pharmacy, Baltimore 21201.
Eur J Pharmacol. 1991 Aug 14;207(4):297-303. doi: 10.1016/0922-4106(91)90003-z.
The muscarinic receptor subtype present in the bovine adrenal medulla was characterized. Hybridization of RNA to highly specific m1-m5 muscarinic receptor cDNA probes detected the presence of only m4 subtype mRNA in this tissue. Muscarinic receptor binding studies using the non-selective ligand [3H]N-methyl-scopolamine showed a single class of binding sites with a maximum density of 19.8 fmol/mg protein and a dissociation constant (KD) of 220 pM in the adrenal medulla, while the M1 selective ligand [3H]telenzepine did not bind detectably. Competition of specific antagonists with [3H]N-methyl-scopolamine for binding to the membranes produced a rank order of potencies with a profile that fitted either the cloned m3 or m4 receptor. In further comparative studies, the adrenal gland of the rat showed the presence of m4 subtype mRNA in addition to the m3 subtype.
对存在于牛肾上腺髓质中的毒蕈碱受体亚型进行了表征。RNA与高度特异性的m1 - m5毒蕈碱受体cDNA探针杂交，结果显示该组织中仅存在m4亚型mRNA。使用非选择性配体[3H]N - 甲基东莨菪碱进行的毒蕈碱受体结合研究表明，肾上腺髓质中存在一类单一的结合位点，最大密度为19.8 fmol/mg蛋白质，解离常数（KD）为220 pM，而M1选择性配体[3H]替仑西平未检测到可察觉的结合。特异性拮抗剂与[3H]N - 甲基东莨菪碱竞争结合膜产生的效价顺序，其特征符合克隆的m3或m4受体。在进一步的比较研究中，大鼠肾上腺除了存在m3亚型外，还显示存在m4亚型mRNA。
