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

Citation
K. Kaunisto et al., An apical membrane Na+/H+ exchanger isoform, NHE-3, is present in the rat epididymal epithelium, PFLUG ARCH, 442(2), 2001, pp. 230-236
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physiology
Journal title
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
ISSN journal
0031-6768 → ACNP
Volume
442
Issue
2
Year of publication
2001
Pages
230 - 236
Database
ISI
SICI code
0031-6768(200105)442:2<230:AAMNEI>2.0.ZU;2-H
Abstract
An acidic milieu is required for sperm maturation and for keeping sperm qui escent during storage in the cauda epididymidis. Previous studies have impl icated a Na+/H+ exchanger (NHE) in epididymal acidification together with c arbonic anhydrase (CA) and vacuolar proton adenosine triphosphatase (H+-ATP ase). The present studies were undertaken to discover whether the NHE isofo rm involved is NHE-3, which is known to mediate Na+ and HCO3- absorption in renal tubules. Using the reverse transcription polymerase chain reaction t echnique (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 NH E3 was present in the apical membranes of the epithelial principal cells an d confirmed that its expression is strongest in the cauda region, decreasin g towards the more proximal regions. Immunoblotting showed a similar expres sion pattern. These results demonstrate that NHE-3 is expressed in the rat epididymal duct with strongest expression in its cauda region. These findin gs are thus consistent with the possibility that NHE-3 in the epididymal du ct is involved in luminal Na+ and/or HCO3- absorption, as in the renal prox imal tubule, and thereby in the regulation of sperm motility and maturation .