title: Inhibition of mucosal glycylsarcosine uptake by acetate in rat distal small intestine.
abstract: Acetate deriving from microbial fermentation may occur at considerable concentrations in the distal small intestine, where it appears to be absorbed by two different mechanisms: acetate-HCO3- exchange and non-ionic diffusion. Whether acetate affects absorption of other nutrients at this intestinal site is not known. Therefore the influence of acetate (30 mmol l-1) on oligopeptide absorption was studied using an in vitro mucosal uptake technique allowing measurement of substrate uptake across the brush border membrane (BBM). Acetate significantly inhibited mucosal uptake of 14C-labelled glycylsarcosine (Gly-Sar) at pH 6 and pH 7 in the presence of sodium. No inhibition occurred in the absence of sodium. Both acetate and the absence of sodium decreased Vmax of mucosal Gly-Sar uptake without substantially affecting the apparent Km value. Since it is well established that Vmax of peptide transport across the intestinal BBM depends on the size of the transmembrane H+ gradient as a driving force the present findings are in accordance with the assumption that acetate inhibits peptide absorption by attenuating the H+ gradient across the BBM, which depends on the presence of sodium.
authors.affiliation: Institute of Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland. scharrer@vetphys.unizh.ch
authors.forename: E
authors.initials: E
authors.lastname: Scharrer
authors.forename: I
authors.initials: I
authors.lastname: Amstutz
authors.forename: B
authors.initials: B
authors.lastname: Grenacher
mesh_terms: D019342:Acetic Acid / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004151:Dipeptides / Q000493:pharmacokinetics*; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004151:Dipeptides; C004194:glycylsarcosine; D019342:Acetic Acid