title: The complete rate equation, including the explicit dependence on Na+ ions, for the influx of alpha-aminoisobutyric acid into mouse brain slices.
abstract: The rate equation, including dependence on Na+-ion concentration for the influx of alpha-aminoisobutyric acid into mouse brain slices incubated in isotonic glucose medium at 37 degrees C, is v = 0.402 S/(1.02(1 + 788/[Na+]2)+S)+0.0477S, where v = influx in mu mol/min, g final wet wt of slices; [Na+] = concentbutyric acid in medium, in mM. This equation shows two kinetically independent, parallel pathways of concentrative uptake: one, saturable and dependent on Na+; the other, unsaturable and independent of Na+. Influx is independent of ionic strength, Cl- ion per se, and a moderate increase in tonicity. The binding of substrate to the saturable carrier depends on the Na+ concentration; the maximum capacity of this carrier does not. For transport, 2 Na+ ions must interact with each saturable transport site. This does not imply coupling between the flux of Na+ and the flux of alpha-aminoisobutyric acid.
mesh_terms: D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002414:Cations, Monovalent; D002712:Chlorides / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology; D007700:Kinetics; D008433:Mathematics; D051379:Mice; D009994:Osmolar Concentration; D012964:Sodium / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology
chemical_list: D000621:Aminoisobutyric Acids; D002414:Cations, Monovalent; D002712:Chlorides; D013395:Sucrose; D012964:Sodium; D002794:Choline