Cohen S R
J Membr Biol. 1980;52(2):95-105. doi: 10.1007/BF01869114.
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.
速率方程描述了在37℃等渗葡萄糖培养基中孵育的小鼠脑切片中，α-氨基异丁酸流入量与Na⁺离子浓度之间的关系，方程为v = 0.402S/(1.02(1 + 788/[Na⁺]²)+S)+0.0477S，其中v为以μmol/min为单位的流入量，g为切片最终湿重；[Na⁺]为培养基中α-氨基异丁酸的浓度，单位为mM。该方程显示了两种动力学上独立的、平行的浓缩摄取途径：一种是可饱和的且依赖于Na⁺；另一种是不饱和的且不依赖于Na⁺。流入量与离子强度、Cl⁻离子本身以及渗透压的适度增加无关。底物与可饱和载体的结合取决于Na⁺浓度；该载体的最大容量则不取决于Na⁺浓度。对于转运而言，每个可饱和转运位点必须有2个Na⁺离子相互作用。但这并不意味着Na⁺通量与α-氨基异丁酸通量之间存在偶联。
