Konrad E M, Thibault G, Schiffrin E L
Laboratory of Pathobiology, Clinical Research Institute of Montreal, Quebec, Canada.
Am J Physiol. 1992 Oct;263(4 Pt 2):R747-55. doi: 10.1152/ajpregu.1992.263.4.R747.
The area postrema (AP) is a brain stem circumventricular organ implicated, among other functions, in central cardiovascular (CV) regulation. Competition binding analysis performed by quantitative in vitro autoradiography demonstrated specific, high-affinity (Kd, 0.32 +/- 0.11 nM), low-capacity (Bmax, 57.5 +/- 10.9 fmol/mg protein) atrial natriuretic factor (ANF) binding sites in the AP. C-ANF [des-(Gln116-Gly120)ANF-(Arg102-Cys121)-NH2] and ANF-(Phe106-Ile113)-NH2 (two ligands endowed with selectivity for the ANF-C receptor), as well as C-type natriuretic peptide (CNP), did not compete noticeably at pathophysiological concentrations for 125I-ANF binding. 125I-[Tyr0]CNP bound to the AP to a much lower extent than 125I-ANF. Electron microscopic autoradiography in vivo disclosed that 125I-ANF was preferentially bound to axon, dendrite, and astrocyte plasmalemma. These studies demonstrate that the AP contains natriuretic peptide binding sites with pharmacological characteristics of the ANF-A and ANF-B but not of the ANF-C receptor subtype. In the AP, ANF interacts with those sites resembling ANF-A receptors. Cellular localization of these binding sites may relate to their possible involvement in the centrally mediated salt and water regulation and/or CV effects of circulating ANF.
最后区（AP）是脑干室周器官，除其他功能外，还参与中枢心血管（CV）调节。通过定量体外放射自显影进行的竞争结合分析表明，在最后区存在特异性、高亲和力（解离常数Kd为0.32±0.11 nM）、低容量（最大结合量Bmax为57.5±10.9 fmol/mg蛋白质）的心房利钠因子（ANF）结合位点。C-ANF [des-(Gln116-Gly120)ANF-(Arg102-Cys121)-NH2] 和ANF-(Phe106-Ile113)-NH2（两种对ANF-C受体具有选择性的配体）以及C型利钠肽（CNP）在病理生理浓度下对125I-ANF结合没有明显竞争。125I-[Tyr0]CNP与最后区的结合程度远低于125I-ANF。体内电子显微镜放射自显影显示，125I-ANF优先结合于轴突、树突和星形胶质细胞质膜。这些研究表明，最后区含有具有ANF-A和ANF-B药理特性而非ANF-C受体亚型药理特性的利钠肽结合位点。在最后区，ANF与类似ANF-A受体的位点相互作用。这些结合位点的细胞定位可能与其可能参与循环ANF的中枢介导的盐和水调节及/或心血管效应有关。
