title: Functional studies of acid transporter in cultured rat epididymal cell.
abstract: OBJECTIVE
  To explore the functional role of vacuolar H(+)-ATPase in the pH regulation of epididymal fluid and its effect on sperm motility.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Physiology laboratory in a university.
  
  
  METHODS
  Immature male Sprague-Dawley rats.
  
  
  METHODS
  The H(+)-ATPase inhibitor was applied to the primary culture of epididymal cells.
  
  
  METHODS
  The intracellular luminal fluid pH and sperm percent motility were recorded.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Life Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Wu-Lin
authors.initials: WL
authors.lastname: Zuo
authors.forename: Jie-Hong
authors.initials: JH
authors.lastname: Huang
authors.forename: Jia-Jie
authors.initials: JJ
authors.lastname: Shan
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.forename: Patrick Y D
authors.initials: PY
authors.lastname: Wong
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Zhou
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D024402:Carbonic Anhydrase II / Q000378:metabolism; D004822:Epididymis / Q000166:cytology* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D018942:Macrolides; D008297:Male; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D013081:Sperm Motility / Q000187:drug effects
chemical_list: D018942:Macrolides; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; C040929:bafilomycin A1; D006180:Proton-Translocating ATPases; D024402:Carbonic Anhydrase II