Segmental distribution of divalent cation transport

Schematic diagram of cells of the distal nephron, including thick ascending limb (TAL) cells, distal convoluted tubule (DCT) cells, and distal convoluted tubule 2/connecting tubule cells (DCT2/CNT). Calcium (Ca²⁺) and magnesium (Mg²⁺) traverse a paracellular pathway along the TAL composed of the claudins 16 and 19. Mg²⁺ is reabsorbed along the DCT via an apical channel, TRPM6. Ca²⁺, by contrast, is reabsorbed along the DCT2/CNT by a different apical channel, TRPV5. Disruption of transport processes along one segment leads to compensation of transport along others.