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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1988 Nov;85(21):8345–8349. doi: 10.1073/pnas.85.21.8345

Cytoplasmic pH determines K+ conductance in fused renal epithelial cells.

H Oberleithner 1, U Kersting 1, M Hunter 1
PMCID: PMC282426  PMID: 2460867

Abstract

The mineralocorticoid hormone aldosterone maintains acid-base balance and K+ homeostasis by regulating H+ and K+ secretory mechanisms in kidney epithelial cells. We have shown recently in the amphibian distal nephron that aldosterone activates a Na+/H+ exchange system in the luminal cell membrane, thus leading to transepithelial H+ secretion and cytoplasmic alkalinization. Since H+ secretory fluxes were paralleled by K+ secretion, it was postulated that the hormone-induced increase of intracellular pH activates the luminally located K+ channels. In "giant" cells fused from individual cells of the distal nephron, we measured simultaneously cytoplasmic pH and cell membrane K+ conductance during acidification of the cell cytoplasm. The experiments show that cell membrane K+ conductance is half-maximal at an intracellular pH of 7.42 and that a positive cooperative interaction exists between K+-channel proteins and H+ (Hill coefficient = 6.5). Moreover, the cellular K+ conductance is most sensitive to cytoplasmic pH in the range modified by aldosterone. This supports the hypothesis that intracellular H+ activity, regulated by the Na+/H+ exchanger, serves as the signal to couple aldosterone-induced K+ secretory flux to H+ secretion in renal tubules.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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