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. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Pflugers Arch. 2013 Oct 6;466(1):10.1007/s00424-013-1370-5. doi: 10.1007/s00424-013-1370-5

Figure 5. Na-K-2Cl cotransport in two types of epithelial cells.

Figure 5

A. Thick ascending limb epithelial cell model showing apical NKCC2 localization. The driving force for NaCl reabsorption is provided by the basolateral Na+/K+ pump. Apical K+ channel (ROMK) delivers K+ in the lumen for NKCC2 function and creates an electropositive lumen. ClCK(A and B) on the basolateral membrane creates a path for Cl− movement and participate in the electronegative blood side. The electrical field generated by the epithelial cells favors the paracellular reabsorption of divalent cations. B. Model of a Cl− secreting epithelial cell with localization of NKCC1 on the basolateral membrane. The cotransporter replenishes Cl− as the anion is transported across the apical through CFTR or other Cl− channels. K+, which enters through the pump and NKCC1, leaves the cell through apical and basolateral K+ channels (not shown). Note that this model can be used for stria vascularis marginal cells (K+ secreting cell) with CFTR substituted for KCNQ1.