Pastuszko A, Wilson D F, Erecinska M
J Biol Chem. 1982 Jul 10;257(13):7514-9.
The energetics of active transport of gamma-aminobutyric acid (GABA) by neuronal synapses has been studied using preparations of synaptosomes from rat brain. The maximal (steady state) accumulation of GABA by synaptosomes was measured as a function of the transmembrane potassium concentration gradient (which is equal to the transmembrane electrical potential in this system), the sodium concentration gradient, and the external chloride concentration. The steady state [GABA]i/[GABA]o increased as the second power of [K+]i/[K+]o which indicates that GABA is transported with a net charge of +2. The GABA gradient was dependent on [Na+]o/[Na+]i to a power of between 1.2 and 2.1 but was almost independent of [Cl-]. It is concluded that a neutral GABA molecule is cotransported with 2 Na+ to give a net charge of +2. The coupling of GABA transport to the transmembrane electrical potential and the Na+ concentration gradient is sufficient to provide the energy for the measured GABA concentration gradient in rat brain synaptosomes.
利用大鼠脑突触体标本，对神经元突触主动转运γ-氨基丁酸（GABA）的能量学进行了研究。测量了突触体对GABA的最大（稳态）积累量，作为跨膜钾浓度梯度（在该系统中等于跨膜电势）、钠浓度梯度和细胞外氯浓度的函数。稳态[GABA]i/[GABA]o随[K+]i/[K+]o的二次方增加，这表明GABA以+2的净电荷进行转运。GABA梯度依赖于[Na+]o/[Na+]i，幂次在1.2至2.1之间，但几乎不依赖于[Cl-]。得出的结论是，一个中性GABA分子与2个Na+协同转运，产生+2的净电荷。GABA转运与跨膜电势和Na+浓度梯度的偶联足以提供大鼠脑突触体中所测GABA浓度梯度的能量。
