A sodium-independent mechanism for L-arginine uptake by rat renal brush border membrane vesicles.
L-arginine accumulation in renal cortex slices or in brush border membrane vesicles differs from that of neutral amino acids and sugars, since it can occur despite a lack of sodium in the incubation medium. L-arginine uptake was measured under different conditions in order to determine the relative importance of the Na+-independent component of this transport. In contrast to D-glucose, which was accumulated into the vesicles only in the presence of a NaCl gradient, the accumulation of L-arginine was induced by NaCl, LiCl, KCl, or choline Cl gradients. The uptakes of L-arginine and D-glucose wer proportional to the membrane potential (inside less than 0), but the presence of Na+ was not required for the L-arginine uptake. No difference was observed in Kj values of the L-arginine uptake measured with low or high concentration of salt (Li+ or Na+). Jmax were also in the same range of magnitude. An influx of D-glucose or L-alanine (Na+-cotransported molecules) induced an increase of the sodium content in vesicles equilibrated with 22Na; the L-arginine uptake did not induce it. These different results suggest that the electrical potential and not the chemical gradient was the major driving force for the L-arginine uptake.
D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D002414:Cations, Monovalent; D005947:Glucose / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism*; D008094:Lithium / Q000494:pharmacology; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology*
D002414:Cations, Monovalent; D001120:Arginine; D008094:Lithium; D012964:Sodium; D005947:Glucose