Similar chloride channels in the connecting tubule and cortical collecting duct of the mouse kidney

Abstract

Using the patch-clamp technique, we investigated Cl- channels on the basolateral membrane of the connecting tubule (CNT) and cortical collecting duct (CCD). We found a approximately 10-pS channel in CNT cell-attached patches. Substitution of sodium gluconate for NaCl in the pipette shifted the reversal potential by +25 mV, whereas N-methyl-D-gluconate chloride had no effect, indicating anion selectivity. On inside-out patches, we determined a selectivity sequence of Cl- > Br- approximately NO3(-) > F-, which is compatible with that of ClC-K2, a Cl- channel in the distal nephron. In addition, the number of open channels (NP(o)) measured in cell-attached patches was significantly increased when Ca2+ concentration or pH in the pipette was increased, which is another characteristic of ClC-K. These findings suggest that the basis for this channel is ClC-K2. A similar Cl- channel was found in CCD patches. Because CNT and CCD are heterogeneous tissues, we studied the cellular distribution of the Cl- channel using recording conditions (KCl-rich solution in the pipette) that allowed us to detect simultaneously Cl- channels and inwardly rectifying K+ channels. We detected Cl- channels alone in 45% and 42% and K+ channels alone in 51% and 58% of CNT and CCD patches, respectively. Cl- and K+ channels were recorded simultaneously from two patches (4% of patches) in the CNT and from none of the patches in the CCD. This indicates that Cl- and K+ channels are located in different cell types, which we suggest may be the intercalated cells and principal cells, respectively.

IGF-1 and insulin exert opposite actions on ClC-K2 activity in the cortical collecting ducts

“…Previous studies suggest the presence of anion conductance on the basolateral membrane of IC (28,30). We first employed patch-clamp electrophysiology in a cellattached configuration in freshly isolated enzymatically treated mouse CCD to perform functional characterization of this conductance.…”

“…For this, we directly monitored changes in the basolateral membrane volt- age using current-clamp configuration upon application of broad spectrum Cl Ϫ channel inhibitors NPPB (100 M) or DIDS (100 M). Previous reports showed that similar concentrations of the antagonists drastically reduced ClC-K2 activity in renal tubule cells (1,28). We focused on IC having values of basolateral membrane voltage of ϳϪ10 mV, in contrast to PC having basolateral membrane voltage of Ϫ70 mV (47).…”

“…Recent experimental evidence indicates that basolateral Cl Ϫ export to the interstitium in the cortical collecting duct (CCD) is mediated by the activity of the chloride ClC-K2 channel present in both A and B types of IC (18,28,42). ClC-K2 (ClC-Kb in humans) is predominantly expressed in the kidney and shares substantial homology with other members of ClC channels (13,42,43).…”

Kir4.1/Kir5.1 channel forms the major K+channel in the basolateral membrane of mouse renal collecting duct principal cells

“…CCDs were microdissected as previously described (26,32), and principal cells were optically identified as flat and polygonal cells in contrast to the round and protuberant intercalated cells (5,26).…”

Nitric oxide inhibits basolateral 10-pS Cl−channels through the cGMP/PKG signaling pathway in the thick ascending limb of C57BL/6 mice

“…We and others (8,9) have previously demonstrated that a 10-pS Cl Ϫ channel was the major type of Cl Ϫ channel in the basolateral membrane of the TAL. The 10-pS Cl Ϫ channel is most likely composed of ClC-K2 owing to their similar biophysical properties and regulatory mechanisms (10,27). However, its regulatory mechanism is not completely understood.…”