An apical membrane Na+/H+ exchanger isoform, NHE-3, is present in the rat epididymal epithelium

Kari Kaunisto, Orson W. Moe, Markku Pelto-Huikko, Martin Traebert, Hannu Rajaniemi

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


An acidic milieu is required for sperm maturation and for keeping sperm quiescent during storage in the cauda epididymidis. Previous studies have implicated a Na+/H+ exchanger (NHE) in epididymal acidification together with carbonic anhydrase (CA) and vacuolar proton adenosine triphosphatase (H+-ATPase). The present studies were undertaken to discover whether the NHE isoform involved is NHE-3, which is known to mediate Na+ and HCO3 - absorption in renal tubules. Using the reverse transcription polymerase chain reaction technique (RT-PCR), Northern blot analysis and in situ hybridization, NHE-3 mRNA was detected mainly in the cauda epididymis and to a lesser extent in other regions of the epididymis. Immunohistochemical studies showed that NHE-3 was present in the apical membranes of the epithelial principal cells and confirmed that its expression is strongest in the cauda region, decreasing towards the more proximal regions. Immunoblotting showed a similar expression pattern. These results demonstrate that NHE-3 is expressed in the rat epididymal duct with strongest expression in its cauda region. These findings are thus consistent with the possibility that NHE-3 in the epididymal duct is involved in luminal Na+ and/or HCO3- absorption, as in the renal proximal tubule, and thereby in the regulation of sperm motility and maturation.

Original languageEnglish (US)
Pages (from-to)230-236
Number of pages7
JournalPflugers Archiv European Journal of Physiology
Issue number2
StatePublished - Jun 6 2001


  • Bicarbonate
  • Immunoblotting
  • Immunohistochemistry
  • Northern blotting
  • Sodium-hydrogen antiporter
  • Sperm motility

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)


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