Wahawisan R, Wallace L J, Gaginella T S
J Pharm Pharmacol. 1986 Feb;38(2):150-3. doi: 10.1111/j.2042-7158.1986.tb04533.x.
Ileal villus and crypt cells exhibit morphological and biochemical differences which may be responsible for functional differences in relation to ion transport. Cholinergic agonists act directly on epithelial cell muscarinic receptors, but it is not known if these receptors exist on both villus and crypt cells. Using the potent muscarinic antagonist 3H-quinuclidinyl benzilate (QNB) we have determined the distribution of muscarinic receptors in rat ileal villus and crypt cells. Plasma membrane preparations from ileal villus and crypt cells possessed a specific, saturable, and high affinity QNB binding site with apparent dissociation constants of 0.23 +/- 0.05 and 0.21 +/- 0.04 nM (mean +/- s.e., n = 6) and densities of 92.2 +/- 2.8 and 90.1 +/- 16.2 fmol (mg protein)-1, respectively. Both types of cells showed similar potencies for agonist and antagonist competition of QNB binding. The muscarinic receptors in membrane fractions from villus cells were found primarily on the basolateral membrane rather than on the brush border membrane. Secretion induced by cholinergic stimulation of the small intestine might, therefore, be due to an effect on both villus and crypt cells as both types contain muscarinic receptors. Furthermore, such stimulation also may result in mucin secretion, as goblet cells were present in the preparation we studied, and receptors on these cells may have contributed to the amount of binding of [3H]QNB.
回肠绒毛和隐窝细胞呈现出形态学和生化方面的差异，这些差异可能与离子转运的功能差异有关。胆碱能激动剂直接作用于上皮细胞的毒蕈碱受体，但尚不清楚这些受体是否同时存在于绒毛和隐窝细胞上。我们使用强效毒蕈碱拮抗剂3H-喹核醇基苯甲酸酯（QNB）来确定大鼠回肠绒毛和隐窝细胞中毒蕈碱受体的分布。回肠绒毛和隐窝细胞的质膜制剂具有一个特异性、可饱和且高亲和力的QNB结合位点，其表观解离常数分别为0.23±0.05和0.21±0.04 nM（平均值±标准误，n = 6），密度分别为92.2±2.8和90.1±16.2 fmol（mg蛋白）-1。两种类型的细胞在QNB结合的激动剂和拮抗剂竞争方面表现出相似的效力。绒毛细胞质膜组分中的毒蕈碱受体主要位于基底外侧膜而非刷状缘膜上。因此，小肠胆碱能刺激诱导的分泌可能是由于对绒毛和隐窝细胞的影响，因为这两种类型的细胞都含有毒蕈碱受体。此外，这种刺激也可能导致粘蛋白分泌，因为在我们研究的制剂中存在杯状细胞，并且这些细胞上的受体可能对[3H]QNB的结合量有贡献。
