title: Na+-independent L-arginine transport in rabbit renal brush border membrane vesicles.
abstract: Na+-independent L-arginine uptake was studied in rabbit renal brush border membrane vesicles. The finding that steady-state uptake of L-arginine decreased with increasing extravesicular osmolality and the demonstration of accelerative exchange diffusion after preincubation of vesicles with L-arginine, but not D-arginine, indicated that the uptake of L-arginine in brush border vesicles was reflective of carrier-mediated transport into an intravesicular space. Accelerative exchange diffusion of L-arginine was demonstrated in vesicles preincubated with L-lysine and L-ornithine, but not L-alanine or L-proline, suggesting the presence of a dibasic amino acid transporter in the renal brush border membrane. Partial saturation of initial rates of L-arginine transport was found with extravesicular [arginine] varied from 0.005 to 1.0 mM. L-Arginine uptake was inhibited by extravesicular dibasic amino acids unlike the Na+-independent uptake of L-alanine, L-glutamine, glycine or L-proline in the presence of extravesicular amino acids of similar structure. L-Arginine uptake was increased by the imposition of an H+ gradient (intravesicular pH less than extravesicular pH) and H+ gradient stimulated uptake was further increased by FCCP. These findings demonstrate membrane-potential-sensitive, Na+-independent transport of L-arginine in brush border membrane vesicles which differs from Na+-independent uptake of neutral and acidic amino acids. Na+-independent dibasic amino acid transport in membrane vesicles is likely reflective of Na+-independent transport of dibasic amino acids across the renal brush border membrane.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D009994:Osmolar Concentration; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D001120:Arginine; D012964:Sodium