potassium-bicarbonate and potassium-sulfate

Intestinal epithelial membrane transport of L-lactic acid was characterized using rabbit jejunal brush-border membrane vesicles (BBMVs). The uptake of L-[(14)C]lactic acid by BBMVs showed an overshoot phenomenon in the presence of outward-directed bicarbonate and/or inward-directed proton gradients. Kinetic analysis of L-[(14)C]lactic acid uptake revealed the involvement of two saturable processes in the presence of both proton and bicarbonate gradients. An arginyl residue-modifying agent, phenylglyoxal, inhibited L-[(14)C]lactic acid transport by the proton cotransporter, but not by the anion antiporter. The initial uptakes of L-[(14)C]lactic acid which are driven by bicarbonate ion and proton gradients were inhibited commonly by monocarboxylic acids and selectively by anion exchange inhibitor 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid and protonophore carbonylcyanide p-trifluoromethoxyphenylhydrazone, respectively. These observations demonstrate that L-lactic acid is transported across the intestinal brush-border membrane by multiple mechanisms, including an anion antiporter and a previously known proton cotransporter.

Topics: Animals; Antiporters; Bicarbonates; Biological Transport; Buffers; Carbonic Anhydrases; Carrier Proteins; Chloride-Bicarbonate Antiporters; Hydrogen-Ion Concentration; Intestinal Absorption; Intestinal Mucosa; Jejunum; Lactic Acid; Male; Membrane Transport Proteins; Microvilli; Potassium Chloride; Potassium Compounds; Protons; Rabbits; Sulfates

Topics: Academies and Institutes; Bicarbonates; Cadaver; Cryoprotective Agents; Humans; Kidney Transplantation; Magnesium Sulfate; Organ Preservation; Potassium Compounds; Sodium Oxybate; Solutions; Sulfates; Time Factors; Tissue Preservation; Tissue Survival; USSR