The renal connecting tubule: Resolved and unresolved issues in Ca²⁺ transport

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• 作者：Nicolas Markadieu ; René ; J. Bindels ; Joost G. Hoenderop
• 关键词：Connecting tubule ; TRPV5 ; Calciotropic hormones ; Klotho
• 刊名：The International Journal of Biochemistry and Cell Biology
• 出版年：2011
• 出版时间：January 2011
• 年：2011
• 卷：43
• 期：1
• 页码：1-4
• 全文大小：342 K

文摘

The renal connecting tubule (CNT) localizes to the distal part of the nephron between the distal convoluted tubule and the collecting duct, and consists of two different cell types: segment-specific and intercalated cells. The former reabsorb water (H₂O), sodium (Na⁺) and calcium (Ca²⁺) ions to the blood compartment, while secreting potassium ions (K⁺) into the pro-urine. The latter cells contribute to the renal control of the acid-base balance. Several factors and hormones tightly regulate these transport processes. Although the CNT reabsorbs only 15 % of filtered Ca²⁺ load, this segment is finally decisive for the amount of Ca²⁺ that appears in the urine. Impaired Ca²⁺ transport across CNT can provoke severe urinary Ca²⁺ excretion, called hypercalciuria. This review mainly focuses on the activity, abundance and expression of the epithelial Ca²⁺ channel named Transient Receptor Potential Vanilloid 5 (TRPV5) that is the gatekeeper of active Ca²⁺ reabsorption in the CNT.