Functional studies of acid transporter in cultured rat epididymal cell

Fertil Steril. 2010 May 15;93(8):2744-9. doi: 10.1016/j.fertnstert.2010.02.042. Epub 2010 Apr 1.


Objective: To explore the functional role of vacuolar H(+)-ATPase in the pH regulation of epididymal fluid and its effect on sperm motility.

Design: Experimental study.

Setting: Physiology laboratory in a university.

Animal(s): Immature male Sprague-Dawley rats.

Intervention(s): The H(+)-ATPase inhibitor was applied to the primary culture of epididymal cells.

Main outcome measure(s): The intracellular luminal fluid pH and sperm percent motility were recorded.

Result(s): Double immunofluorescence of H(+)-ATPase and carbonic anhydrase II in primary culture of cauda epididymal epithelial cells showed that the system was a suitable model for investigation of acid secretion by clear cells. Clear cells were pharmacologically distinct from principal cells in acid/base transportation. The intracellular pH recovery from cellular acidification was suppressed by the H(+)-ATPase inhibitor bafilomycin A1(100 nM) and the Na(+)/H(+) exchanger inhibitor amiloride (1 mM) by 85% and 54%, respectively. These results suggest that, in addition to Na(+)/H(+) exchanger, clear cells actively pump proton from cytoplasm into extracellular space through H(+)-ATPase. In addition, inhibition of H(+)-ATPase by bafilomycin A1 blocked the acidification of luminal fluid with IC(50) values of 12 nM, which supports that H(+)-ATPase acidifies the luminal fluid. We also confirm that the acid fluid regulates rat cauda sperm motility.

Conclusion(s): The present work shows that clear cells, the minority cell type of epididymal cell population, play an important role in the pH regulation of epididymal fluid by H(+)-ATPase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amiloride / pharmacology
  • Animals
  • Carbonic Anhydrase II / metabolism
  • Epididymis / cytology*
  • Epididymis / metabolism
  • Hydrogen-Ion Concentration
  • Intracellular Fluid / metabolism
  • Macrolides
  • Male
  • Proton-Translocating ATPases / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Sodium-Hydrogen Exchangers / metabolism
  • Sperm Motility / drug effects


  • Macrolides
  • Sodium-Hydrogen Exchangers
  • Amiloride
  • bafilomycin A1
  • Proton-Translocating ATPases
  • Carbonic Anhydrase II