Herten M, Lenz W, Gerzer R, Drummer C
Institut für Luft- und Raumfahrtmedizin, Deutsches Forschungszentrum für Luft und Raumfahrt (DLR), Köln, Germany.
Nephrol Dial Transplant. 1998 Oct;13(10):2529-35. doi: 10.1093/ndt/13.10.2529.
The natriuretic peptide urodilatin was first isolated from human urine and may be one of the important mediators of natriuresis, while the atrial natriuretic peptide alpha-ANP, the circulating member of the family, rather seems to play a role in cardiovascular regulation. Although the renal expression of the common propeptide for urodilatin and alpha-ANP has been detected in rat and pig, it is not yet shown that urodilatin is synthesized in human kidney.
Immunohistochemically we localized urodilatin with an urodilatin-antibody, which does not cross-react with alpha-ANP, the ANP propeptide, brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Radiolabelled urodilatin binding was examined autoradiographically.
We could demonstrate that urodilatin is present in human distal tubular cells, in which we could also localize propeptide immunoreactivity. The glomeruli, the cells of the proximal tubule, and the collecting duct did not show any urodilatin immunoreactivity. In human kidney homogenate the urodilatin content was 4600 + 520 fmol/g protein (n = 6). The renal concentration of BNP and CNP, mainly localized in the distal tubule, was much lower at 40 + 8 and 400+/-50 fmol/g protein (n=6) respectively. Furthermore the autoradiographic examinations showed that radiolabelled urodilatin binds to natriuretic peptide receptors in the glomeruli, blood vessels, and collecting ducts.
Our data suggest that urodilatin may be the predominant representative of natriuretic peptides in human kidneys. Urodilatin being synthesized in the distal tubular region may be transported as a paracrine factor to the collecting duct, where it exerts its suppressing effect on the sodium reabsorption by stimulating the guanylyl cyclase A.
利钠肽尿舒张素最初是从人尿中分离出来的，可能是利钠作用的重要介质之一，而该家族的循环成员心房利钠肽α-ANP似乎在心血管调节中发挥作用。尽管在大鼠和猪中已检测到尿舒张素和α-ANP共同前体肽的肾脏表达，但尚未证明尿舒张素在人肾脏中合成。
我们用一种尿舒张素抗体进行免疫组织化学定位，该抗体与α-ANP、ANP前体肽、脑利钠肽（BNP）和C型利钠肽（CNP）无交叉反应。通过放射自显影检查放射性标记的尿舒张素结合情况。
我们能够证明尿舒张素存在于人类远端肾小管细胞中，在这些细胞中我们也能定位前体肽免疫反应性。肾小球、近端肾小管细胞和集合管未显示任何尿舒张素免疫反应性。在人肾匀浆中，尿舒张素含量为4600 + 520 fmol/g蛋白质（n = 6）。主要定位于远端肾小管的BNP和CNP的肾脏浓度分别低得多，为40 + 8和400 ± 50 fmol/g蛋白质（n = 6）。此外，放射自显影检查表明，放射性标记的尿舒张素与肾小球、血管和集合管中的利钠肽受体结合。
我们的数据表明，尿舒张素可能是人肾脏中利钠肽的主要代表。在远端肾小管区域合成的尿舒张素可能作为旁分泌因子转运至集合管，在那里它通过刺激鸟苷酸环化酶A对钠重吸收发挥抑制作用。
