大鼠空肠黏膜上皮细胞酪酪肽受体的分布与特性

Distribution and characters of peptide YY receptor in rat jejunum epithelial cell

目的检测正常大鼠空肠黏膜酪酪肽(PYY)受体的分布并测定反映酪酪肽受体特性的基本参数,初步阐明酪酪肽的作用位点和作用特点。方法用125I标记酪酪肽并对其进行受体放射分析,测得酪酪肽受体的平衡解离常数,最大结合容量及Hill系数。结果正常大鼠空肠黏膜上皮细胞酪酪肽受体的平衡解离常数(Kd)为(386.69±129.95)pmol/L,最大结合容量(Bmax)为(303.21±116.85)fmol/mg蛋白;Hill系数为1。酪酪肽受体为高亲和力受体。结论正常大鼠空肠黏膜上皮细胞有酪酪肽受体的分布,酪酪肽受体之间无正负协同效应;酪酪肽受体对PYY具有高亲和性;可能有PYY直接与空肠黏膜上皮酪酪肽受体结合而直接抑制空肠黏膜的分泌。

Objective To detect normal rat jejunum epithelial cells to learn about the distribution of peptide YY （PYY） receptor and measured two important parameters of PYY receptor so as to explore the target that PYY binds to and display its physiological function. Methods Receptor radioligand assay was conducted by using ^125Ⅰ. PYY to detect normal rat jejunum epithelial cells. We also measured receptor dissociation constant （Kd）, the affinity or the ability that the receptor could bind ligand; maximum binding capacity （Bmax）, the concentration of binding site; and Hill coefficient. Results There were PYY receptors in normal rat jejunum epithelial cells. Dissociation constant （Kd） of PYY receptor was （386.69±129.95）pmol/L. Maximum binding capacity （Bmax） was （303.21±116.85） fmol/mg protein. Hill coefficient was 1. PYY receptor had high affinity. Conclusion There are distributions of PYY receptors in normal rat jejunum epithelial cells. Kd means that PYY receptor has high affinity. Bmax means that the number of receptors is limited and decides the characters of saturability. We think that PYY directly inhibits secretion by binding to PYY receptor in jejunum epithelial cells when PYY inhibiting jejunum secretion.