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

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 obse...

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Published in:American journal of physiology. Renal physiology 2008-06, Vol.294 (6), p.F1398-F1407
Main Authors: Lachheb, Sahran, Cluzeaud, Françoise, Bens, Marcelle, Genete, Mathieu, Hibino, Hiroshi, Lourdel, Stéphane, Kurachi, Yoshihisa, Vandewalle, Alain, Teulon, Jacques, Paulais, Marc
Format: Article
Language:English
Subjects:
Animals
Cell Polarity - physiology
Cells
Cloning, Molecular
Immunohistochemistry
In Vitro Techniques
Kidney Cortex - physiology
Kidney Tubules, Collecting - cytology
Kidney Tubules, Collecting - physiology
Kidneys
Kir5.1 Channel
Male
Mice
Mice, Inbred Strains
Models, Biological
Patch-Clamp Techniques
Potassium
Potassium Channels, Inwardly Rectifying - genetics
Potassium Channels, Inwardly Rectifying - physiology
Potassium, Dietary - pharmacokinetics
Proteins
RNA, Messenger - metabolism
Rodents
Sodium, Dietary - pharmacokinetics
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Summary: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.
ISSN:1931-857X
1522-1466
DOI:10.1152/ajprenal.00288.2007