Bianchi C, Thibault G, De Léan A, Genest J, Cantin M
Laboratory of Pathobiology, Clinical Research Institute of Montreal, Quebec, Canada.
Am J Physiol. 1989 Feb;256(2 Pt 1):G436-41. doi: 10.1152/ajpgi.1989.256.2.G436.
We have studied the localization and the characterization of atrial natriuretic factor (ANF) binding sites by radioautographic techniques. Quantitative in vitro radioautography with a computerized microdensitometer demonstrated the presence of high-affinity, low-capacity 125I-ANF-(99-126) binding sites (Kd, 48 pM; Bmax, 63 fmol/mg protein) mainly in the villi of 20-microns slide-mounted transverse sections of the rat jejunum. Competition curves showed 50% inhibitory concentrations of 55 and 1,560 pM for ANF-(99-126) and ANF-(103-123), respectively. In vivo electron microscope radioautography showed that 80% of the silver grains were localized on the lamina propria fibroblast-like cells, 18% on mature enterocytes, and 2% on capillaries. Bradykinin and adrenocorticotropin did not compete with ANF binding. These results demonstrate that ANF binding sites in the rat jejunum possess the pharmacological characteristics of functional ANF receptors encountered in other rat tissues, and ultrastructural radioautographs show their cellular distribution. Taken together, these results demonstrate the presence and the localization of specific binding sites for ANF in the jejunal villi of the rat small intestine.
我们通过放射自显影技术研究了心房钠尿肽（ANF）结合位点的定位及特性。使用计算机化显微密度计进行的定量体外放射自显影显示，在大鼠空肠20微米厚、载玻片固定的横切片绒毛中主要存在高亲和力、低容量的125I-ANF-(99-126)结合位点（解离常数Kd为48皮摩尔；最大结合容量Bmax为63飞摩尔/毫克蛋白质）。竞争曲线显示，ANF-(99-126)和ANF-(103-123)的50%抑制浓度分别为55皮摩尔和1560皮摩尔。体内电子显微镜放射自显影显示，80%的银粒定位于固有层成纤维细胞样细胞，18%定位于成熟肠上皮细胞，2%定位于毛细血管。缓激肽和促肾上腺皮质激素不与ANF结合竞争。这些结果表明，大鼠空肠中的ANF结合位点具有在大鼠其他组织中发现的功能性ANF受体的药理学特性，超微结构放射自显影片显示了它们的细胞分布。综上所述，这些结果证明了大鼠小肠空肠绒毛中存在ANF特异性结合位点及其定位。
