Cultured ruminal epithelial cells express a large-conductance channel permeable to chloride, bicarbonate, and acetate

Pflugers Arch. 2009 Mar;457(5):1003-22. doi: 10.1007/s00424-008-0566-6. Epub 2008 Aug 21.

Abstract

The absorption of short-chain fatty acids (SCFA) from the rumen requires efficient mechanisms for both apical uptake and basolateral extrusion. Previous studies suggest that the rumen expresses a basolateral chloride conductance that might be permeable to SCFA. In order to characterize this conductance in more detail, isolated cultured ruminal epithelial cells were studied with the patch-clamp technique, revealing a whole-cell conductance with p(Cl(-)) approximately p(NO(3) (-)) > p(HCO(3) (-)) > p(acetate(-)) > p(gluconate(-)). Currents could be blocked by diisothiocyanato-stilbene-2,2'-disulfonic acid (1 mmol l(-1) > 100 micromol l(-1)), 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (50 micromol l(-1)), niflumic acid (100 micromol l(-1)), and p-chloromercuribenzoate (1 mmol l(-1)). Single-channel conductance was 350 +/- 7 pS for chloride and 142 +/- 7 pS for acetate. Open probability could be fitted with a three-state gating model. We propose a role for this channel in mediating the permeation of chloride, bicarbonate, and acetate across the basolateral membrane of the ruminal epithelium.

MeSH terms

  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / pharmacology
  • Acetates / metabolism*
  • Animals
  • Bicarbonates / metabolism*
  • Cells, Cultured
  • Chlorides / metabolism*
  • Epithelial Cells / metabolism
  • Fatty Acids, Volatile / metabolism
  • Gluconates / metabolism
  • Ion Channel Gating / drug effects*
  • Nitrates / metabolism
  • Nitrobenzoates / pharmacology
  • Patch-Clamp Techniques
  • Potassium / metabolism
  • Rumen / cytology
  • Rumen / metabolism*
  • Sheep
  • Sodium / metabolism
  • p-Chloromercuribenzoic Acid / pharmacology

Substances

  • Acetates
  • Bicarbonates
  • Chlorides
  • Fatty Acids, Volatile
  • Gluconates
  • Nitrates
  • Nitrobenzoates
  • 5-nitro-2-(3-phenylpropylamino)benzoic acid
  • p-Chloromercuribenzoic Acid
  • Sodium
  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
  • gluconic acid
  • Potassium