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

Abstract : K(+) channels in the basolateral membrane of mouse cortical collecting duct (CCD) principal cells were identified with patch-clamp technique, real-time PCR, and immunohistochemistry. In cell-attached membrane patches, three K(+) channels with conductances of approximately 75, 40, and 20 pS were observed, but the K(+) channel with the intermediate conductance (40 pS) predominated. In inside-out membrane patches exposed to an Mg(2+)-free medium, the current-voltage relationship of the intermediate-conductance channel was linear with a conductance of 38 pS. Addition of 1.3 mM internal Mg(2+) had no influence on the inward conductance (G(in) = 35 pS) but reduced outward conductance (G(out)) to 13 pS, yielding a G(in)/G(out) of 3.2. The polycation spermine (6 x 10(-7) M) reduced its activity on inside-out membrane patches by 50% at a clamp potential of 60 mV. Channel activity was also dependent on intracellular pH (pH(i)): a sigmoid relationship between pH(i) and channel normalized current (NP(o)) was observed with a pK of 7.24 and a Hill coefficient of 1.7. By real-time PCR on CCD extracts, inwardly rectifying K(+) (Kir)4.1 and Kir5.1, but not Kir4.2, mRNAs were detected. Kir4.1 and Kir5.1 proteins cellularly colocalized with aquaporin 2 (AQP2), a specific marker of CCD principal cells, while AQP2-negative cells (i.e., intercalated cells) showed no staining. Dietary K(+) had no influence on the properties of the intermediate-conductance channel, but a Na(+)-depleted diet increased its open probability by approximately 25%. We conclude that the Kir4.1/Kir5.1 channel is a major component of the K(+) conductance in the basolateral membrane of mouse CCD principal cells.
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https://hal.sorbonne-universite.fr/hal-02453208
Contributor : Stéphane Lourdel Connect in order to contact the contributor
Submitted on : Thursday, January 23, 2020 - 4:46:37 PM
Last modification on : Wednesday, March 23, 2022 - 3:51:20 PM

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Sahran Lachheb, Françoise Cluzeaud, Marcelle Bens, Mathieu Genete, Hiroshi Hibino, et al.. Kir4.1/Kir5.1 channel forms the major K + channel in the basolateral membrane of mouse renal collecting duct principal cells. AJP Renal Physiology, American Physiological Society, 2008, 294 (6), pp.F1398-F1407. ⟨10.1152/ajprenal.00288.2007⟩. ⟨hal-02453208⟩

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