Stoeckel M E, Freund-Mercier M J
Laboratoire de Physiologie Générale, URA, Centre National de la Recherche Scientifique, Strasbourg, France.
Am J Physiol. 1989 Aug;257(2 Pt 2):F310-4. doi: 10.1152/ajprenal.1989.257.2.F310.
Specific oxytocin (OT)-binding sites were localized in the rat kidney with use of a selective 125I-labeled OT antagonist (125I-OTA). High concentrations of OT binding sites were detected on the juxtaglomerular apparatus with use of the conventional film autoradiographic technique. No labeling occurred on other renal structures. The cellular localization of the OT binding sites within the juxtaglomerular apparatus was studied in light microscope autoradiography, on semithin sections from paraformaldehyde-fixed kidney slices incubated in the presence of 125I-OTA. These preparations revealed selective labeling of the macula densa, mainly concentrated at the basal pole of the cells. Control experiments showed first that 125I-OTA binding characteristics were not noticeably altered by prior paraformaldehyde fixation of the kidneys and second that autoradiographic detection of the binding sites was not impaired by histological treatments following binding procedures. In view of the role of the macula densa in the tubuloglomerular feedback, the putative OT receptors of this structure might mediate the stimulatory effect of OT on glomerular filtration.
利用选择性125I标记的催产素拮抗剂（125I-OTA），在大鼠肾脏中定位了特异性催产素（OT）结合位点。采用传统的胶片放射自显影技术，在肾小球旁器上检测到高浓度的OT结合位点。在其他肾脏结构上未出现标记。利用光学显微镜放射自显影技术，在经多聚甲醛固定的肾切片的半薄切片上，研究了肾小球旁器内OT结合位点的细胞定位，这些切片在125I-OTA存在的情况下孵育。这些制剂显示致密斑有选择性标记，主要集中在细胞的基底部。对照实验首先表明，肾脏预先用多聚甲醛固定不会明显改变125I-OTA的结合特性，其次表明结合程序后的组织学处理不会损害结合位点的放射自显影检测。鉴于致密斑在肾小管-肾小球反馈中的作用，该结构中假定的OT受体可能介导OT对肾小球滤过的刺激作用。
