Referenced in: none

Automatically associated channels: TRP , TRPV , TRPV5

Title: The renal connecting tubule: Resolved and unresolved issues in Ca(2+) transport.

Authors: Nicolas Markadieu, René J Bindels, Joost G Hoenderop

Journal, date & volume: Int. J. Biochem. Cell Biol., 2011 Jan , 43, 1-4

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20969972

Abstract
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 (H(2)O), sodium (Na(+)) and calcium (Ca(2+)) 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 Ca(2+) load, this segment is finally decisive for the amount of Ca(2+) that appears in the urine. Impaired Ca(2+) transport across CNT can provoke severe urinary Ca(2+) excretion, called hypercalciuria. This review mainly focuses on the activity, abundance and expression of the epithelial Ca(2+) channel named Transient Receptor Potential Vanilloid 5 (TRPV5) that is the gatekeeper of active Ca(2+) reabsorption in the CNT.