title: Sodium coupled bicarbonate influx regulates intracellular and apical pH in cultured rat caput epididymal epithelium.
abstract: BACKGROUND
  The epithelium lining the epididymis provides an optimal acidic fluid microenvironment in the epididymal tract that enable spermatozoa to complete the maturation process. The present study aims to investigate the functional role of Na(+)/HCO(3)(-) cotransporter in the pH regulation in rat epididymis.
  
  
  RESULTS
  Immunofluorescence staining of pan cytokeratin in the primary culture of rat caput epididymal epithelium showed that the system was a suitable model for investigating the function of epididymal epithelium. Intracellular and apical pH were measured using the fluorescent pH sensitive probe carboxy-seminaphthorhodafluor-4F acetoxymethyl ester (SNARF-4F) and sparklet pH electrode respectively to explore the functional role of rat epididymal epithelium. In the HEPES buffered Krebs-Henseleit (KH) solution, the intracellular pH (pHi) recovery from NH(4)Cl induced acidification in the cultured caput epididymal epithelium was completely inhibited by amiloride, the inhibitor of Na(+)/H(+) exchanger (NHE). Immediately changing of the KH solution from HEPES buffered to HCO(3)(-) buffered would cause another pHi recovery. The pHi recovery in HCO(3)(-) buffered KH solution was inhibited by 4, 4diisothiocyanatostilbene-2,2-disulfonic acid (DIDS), the inhibitor of HCO(3)(-) transporter or by removal of extracellular Na(+). The extracellular pH measurement showed that the apical pH would increase when adding DIDS to the apical side of epididymal epithelial monolayer, however adding DIDS to the basolateral side had no effect on apical pH.
  
  
  CONCLUSIONS
  The present study shows that sodium coupled bicarbonate influx regulates intracellular and apical pH in cultured caput epididymal epithelium.
authors: School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors: Wu-Lin
authors: WL
authors: Zuo
authors: Sheng
authors: S
authors: Li
authors: Jie-Hong
authors: JH
authors: Huang
authors: Deng-Liang
authors: DL
authors: Yang
authors: Geng
authors: G
authors: Zhang
authors: Si-Liang
authors: SL
authors: Chen
authors: Ye-Chun
authors: YC
authors: Ruan
authors: Ke-Nan
authors: KN
authors: Ye
authors: Christopher H K
authors: CH
authors: Cheng
authors: Wen-Liang
authors: WL
authors: Zhou
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000143:Acids / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D027982:Sodium-Bicarbonate Symporters / Q000378:metabolism
chemical_list: D000143:Acids; D001639:Bicarbonates; D027982:Sodium-Bicarbonate Symporters; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid