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A Chloride Channel at the Basolateral Membrane of the Distal-convoluted Tubule

Abstract : The distal-convoluted tubule (DCT) of the kidney absorbs NaCl mainly via an Na+-Cl- cotransporter located at the apical membrane, and Na+, K+ ATPase at the basolateral side. Cl- transport across the basolateral membrane is thought to be conductive, but the corresponding channels have not yet been characterized. In the present study, we investigated Cl- channels on microdissected mouse DCTs using the patch-clamp technique. A channel of approximately 9 pS was found in 50% of cell-attached patches showing anionic selectivity. The NPo in cell-attached patches was not modified when tubules were preincubated in the presence of 10-5 M forskolin, but the channel was inhibited by phorbol ester (10-6 M). In addition, NPo was significantly elevated when the calcium in the pipette was increased from 0 to 5 mM (NPo increased threefold), or pH increased from 6.4 to 8.0 (NPo increased 15-fold). Selectivity experiments conducted on inside-out patches showed that the Na+ to Cl- relative permeability was 0.09, and the anion selectivity sequence Cl(-)--I(-) > Br(-)--NO3(-) > F(-). Intracellular NPPB (10-4 M) and DPC (10-3 M) blocked the channel by 65% and 80%, respectively. The channel was inhibited at acid intracellular pH, but intracellular ATP and PKA had no effect. ClC-K Cl- channels are characterized by their sensitivity to the external calcium and to pH. Since immunohistochemical data indicates that ClC-K2, and perhaps ClC-K1, are present on the DCT basolateral membrane, we suggest that the channel detected in this study may belong to this subfamily of the ClC channel family.
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https://www.hal.inserm.fr/inserm-02448174
Contributor : Marc Paulais <>
Submitted on : Wednesday, January 22, 2020 - 10:07:51 AM
Last modification on : Wednesday, February 5, 2020 - 1:28:26 AM

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Stéphane Lourdel, Marc Paulais, Pedro Marvao, Antoine Nissant, Jacques Teulon. A Chloride Channel at the Basolateral Membrane of the Distal-convoluted Tubule. Journal of General Physiology, Rockefeller University Press, 2003, 121 (4), pp.287-300. ⟨10.1085/jgp.200208737⟩. ⟨inserm-02448174⟩

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