Szabo A, Merke J, Thomasset M, Ritz E
Department of Internal Medicine, University of Heidelberg, Germany.
Eur J Clin Invest. 1991 Oct;21(5):521-6. doi: 10.1111/j.1365-2362.1991.tb01404.x.
In parathyroids of uraemic patients or animals, decreased specific binding of 1,25(OH)2D3 has been observed and implicated in the genesis of secondary hyperparathyroidism of renal failure. We re-examined binding of 1,25(OH)2D3 using chromatin preparations for receptor characterization which differed from previous studies (a) by inclusion of protease inhibitors (PMSF, aprotinin) and molybdate in the extraction buffer and (b) by omitting the K-extraction step. With this method, the Nmax in the intestinal mucosa and parathyroids of uraemic animals was significantly higher, while the receptor sedimentation constant (S), DNA affinity and KD were all unchanged. The ratio of occupied to total receptors was not significantly altered. The regulation of 1,25(OH)2D3 receptors in response to acute injection of 1,25(OH)2D3 was abnormal. Calbindin-D9k concentration in the intestines of uraemic and control rats was comparable both before and after administration of 1,25(OH)2D3. The present data demonstrate (a) increased 1,25(OH)2D3 receptors and (b) unchanged 1,25(OH)2D3-dependent synthesis of calcium binding protein (CaBP) in experimental uraemia.
在尿毒症患者或动物的甲状旁腺中，已观察到1,25(OH)₂D₃的特异性结合减少，这与肾衰竭继发性甲状旁腺功能亢进的发生有关。我们使用染色体制剂重新检测了1,25(OH)₂D₃的结合情况，以表征受体，该方法与以往研究不同之处在于：(a)在提取缓冲液中加入了蛋白酶抑制剂（苯甲基磺酰氟、抑肽酶）和钼酸盐；(b)省略了钾提取步骤。采用这种方法，尿毒症动物肠黏膜和甲状旁腺中的Nmax显著更高，而受体沉降常数(S)、DNA亲和力和KD均未改变。占据受体与总受体的比例没有显著变化。急性注射1,25(OH)₂D₃后，1,25(OH)₂D₃受体的调节异常。给予1,25(OH)₂D₃前后，尿毒症大鼠和对照大鼠肠道中的钙结合蛋白-D9k浓度相当。目前的数据表明，在实验性尿毒症中：(a) 1,25(OH)₂D₃受体增加；(b) 1,25(OH)₂D₃依赖性钙结合蛋白(CaBP)的合成未改变。
