Publikationsdatenbank

Epithelia of the ovine and bovine forestomach express basolateral maxi-anion channels permeable to the anions of short-chain fatty acids (2014)

Art

Zeitschriftenartikel / wissenschaftlicher Beitrag

Autoren

Georgi, M. I. (WE 2)

Rosendahl, Julia (WE 2)

Ernst, Franziska (WE 2)

Gunzel, D.

Aschenbach, Jörg R. (WE 2)

Martens, Holger (WE 2)

Stumpff, Friederike (WE 2)

Quelle

Pflügers Archiv : European journal of physiology

Bandzählung: 466

Heftzählung: 9

Seiten: 1968 – 1712

ISSN: 1432-2013

Sprache

Englisch

Verweise

DOI: 10.1007/s00424-013-1386-x

Pubmed: 24240698

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

It has long been established that the absorption of short-chain fatty acids (SCFA) across epithelia stimulates sodium proton exchange. The apically released protons are not available as countercations for the basolateral efflux of SCFA anions and a suitable transport model is lacking. Patch clamp and microelectrode techniques were used to characterize an anion conductance expressed by cultured cells of the sheep and bovine rumen and the sheep omasum and to localize the conductance in the intact tissue. Cells were filled with a Na-gluconate solution and superfused with sodium salts of acetate, propionate, butyrate, or lactate. Reversal potential rose and whole cell current at +100 mV decreased with the size of the anion. Anion-induced currents could be blocked by diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS), NPPB (200 μmol l-1), or pCMB (1 mmol l-1). In patches of bovine ruminal cells, single channels were observed with a conductance for chloride (327 ± 11 pS), acetate (115 ± 8 pS), propionate (102 ± 10 pS), butyrate (81 ± 2 pS), and gluconate (44 ± 3 pS). Channels expressed by sheep rumen and omasum were similar. Microelectrode experiments suggest basolateral localization. In conclusion, forestomach epithelia express basolateral maxi-anion channels with a permeability sequence of chloride > acetate > propionate > butyrate. SCFA absorption may resemble functionally coupled transport of NaCl, with the Na+/K+-ATPase driving the basolateral efflux of the anion through a channel. Since protons are apically extruded, the model accurately predicts that influx of buffers with saliva is essential for the pH homeostasis of the ruminant forestomach.