Collecting duct-specific Rh C glycoprotein deletion alters basal and acidosis-stimulated renal ammonia excretion

Hyun Wook Lee, Jill W. Verlander, Jesse M. Bishop, Peter Igarashi, Mary E. Handlogten, I. David Weiner

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

NH3 movement across plasma membranes has traditionally been ascribed to passive, lipidphase diffusion. However, ammonia-specific transporters, Mep/Amt proteins, are present in primitive organisms and mammals express orthologs of Mep/Amt proteins, the Rh glycoproteins. These findings suggest that the mechanisms of NH3 movement in mammalian tissues should be reexamined. Rh C glycoprotein (Rhcg) is expressed in the collecting duct, where NH3 secretion is necessary for both basal and acidosis-stimulated ammonia transport. To determine whether the collecting duct secretes NH3 via Rhcg or via lipid-phase diffusion, we generated mice with collecting duct-specific Rhcg deletion (CD-KO). CD-KO mice had loxP sites flanking exons 5 and 9 of the Rhcg gene (Rhcgfl/fl) and expressed Cre-recombinase under control of the Ksp-cadherin promoter (Ksp-Cre). Control (C) mice were Rhcgfl/fl but Ksp-Cre negative. We confirmed kidney-specific genomic recombination using PCR analysis and collecting duct-specific Rhcg deletion using immunohistochemistry. Under basal conditions, urinary ammonia excretion was less in KO vs. C mice; urine pH was unchanged. After acid-loading for 7 days, CD-KO mice developed more severe metabolic acidosis than did C mice. Urinary ammonia excretion did not increase significantly on the first day of acidosis in CD-KO mice, despite an intact ability to increase urine acidification, whereas it increased significantly in C mice. On subsequent days, urinary ammonia excretion slowly increased in CD-KO mice, but was always significantly less than in C mice. We conclude that collecting duct Rhcg expression contributes to both basal and acidosis-stimulated renal ammonia excretion, indicating that collecting duct ammonia secretion is, at least in part, mediated by Rhcg and not solely by lipid diffusion.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Physiology
Volume296
Issue number6
DOIs
StatePublished - Jun 2009

Fingerprint

Acidosis
Ammonia
EphB6 Receptor
Cadherins
glycoprotein gC, herpes simplex virus type 1
Renal Elimination
Urine
Lipids
Genetic Recombination
Mammals
Exons
Glycoproteins
Immunohistochemistry
Cell Membrane
Kidney
Polymerase Chain Reaction
Acids

Keywords

  • Acid-base
  • NH movement

ASJC Scopus subject areas

  • Physiology
  • Urology

Cite this

Collecting duct-specific Rh C glycoprotein deletion alters basal and acidosis-stimulated renal ammonia excretion. / Lee, Hyun Wook; Verlander, Jill W.; Bishop, Jesse M.; Igarashi, Peter; Handlogten, Mary E.; Weiner, I. David.

In: American Journal of Physiology - Renal Physiology, Vol. 296, No. 6, 06.2009.

Research output: Contribution to journalArticle

Lee, Hyun Wook ; Verlander, Jill W. ; Bishop, Jesse M. ; Igarashi, Peter ; Handlogten, Mary E. ; Weiner, I. David. / Collecting duct-specific Rh C glycoprotein deletion alters basal and acidosis-stimulated renal ammonia excretion. In: American Journal of Physiology - Renal Physiology. 2009 ; Vol. 296, No. 6.
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