Regulation of renal calcium transporter expressions and phosphate metabolism

食盐摄入增加尿钙排泄，可能导致骨质疏松症和尿路结石形成。在饮食盐负荷的大鼠中，我们发现远端小管上钙重吸收分子的表达增加，而促进近端小管内钙重吸收的分子claudin 2的蛋白表达减少。在肾脏中，Na+/Ca~(2+)交换器1(NCX1)主要在远端小管和血管平滑肌中表达。在体大鼠肾皮质应用NCX1抑制剂可在不改变钙动力学的情况下降低血磷，并减少尿蛋白和肾小球大小。这些观察表明，肾脏NCX1在磷酸盐代谢以及控制尿蛋白和肾小球内压方面发挥了作用，这些都是慢性肾脏疾病的重要方面。

Dietary NaCl intake increases the excretion of calcium into urine, which may lead to osteoporosis and urinary tract stone formation. In dietary NaCl-loaded rats, we have found that the expression of calcium reabsorbing molecules on the distal tubule increases while the protein expression of a molecule that enhances calcium reabsorption in the proximal tubule, claudin 2, is decreased. NaCl ingestion may lead to calcium loss in part via reduced expression of claudin 2. In the kidney, Na+/Ca2+exchanger 1 (NCX1) is mainly expressed in the distal tubule and the vascular smooth muscle. In vivo renal cortical administration of NCX1 inhibitor in rats lead to a decrease in serum phosphate without altering calcium dynamics, and it also decreased urinary protein and glomerular size. These observations suggest a role of renal NCX1 in phosphate metabolism and control of urinary protein and intraglomerular pressure, which are important aspects of chronic kidney disease.