Identification and localization of BK-β subunits in the distal nephron of the mouse kidney

P. Richard Grimm, Ruth M. Foutz, Robert Brenner, Steven C. Sansom

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Large-conductance, Ca2+-activated K+ channels (BK), comprised of pore-forming α- and accessory β-subunits, secrete K + in the distal nephron under high-flow and high-K+ diet conditions. BK channels are detected by electrophysiology in many nephron segments; however, the accessory β-subunit associated with these channels has not been determined. We performed RT-PCR, Western blotting, and immunohistochemical staining to determine whether BK-β1 is localized to the connecting tubule's principal-like cells (CNT) or intercalated cells (ICs), and whether BK-β2-4 are present in other distal nephron segments. RT-PCR and Western blots revealed that the mouse kidney expresses BK-β1, BK-β2, and BK-β4. Available antibodies in conjunction with BK-β1 -/- and BK-β4-/- mice allowed the specific localization of BK-β1 and BK-β4 in distal nephron segments. Immunohistochemical staining showed that BK-β1 is localized in the CNT but not ICs of the connecting tubule. The localization of BK-β4 was discerned using an anti-BK-β4 antibody on wild-type tissue and anti-GFP on GFP-replaced BK-β4 mouse (BK-β4-/-) tissue. Both antibodies (anti-BK-β4 and anti-GFP) localized BK-β4 to the thick ascending limb (TAL), distal convoluted tubule (DCT), and ICs of the distal nephron. It is concluded that BK-β1 is narrowly confined to the apical membrane of CNTs in the mouse, whereas BK-β4 is expressed in the TAL, DCT, and ICs.

Original languageEnglish (US)
Pages (from-to)F350-F359
JournalAmerican Journal of Physiology - Renal Physiology
Volume293
Issue number1
DOIs
StatePublished - Jul 2007

Keywords

  • BK
  • Connecting tubule
  • Intercalated cells
  • Maxi K
  • Mice
  • Thick ascending limb

ASJC Scopus subject areas

  • Physiology
  • Urology

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