Kontro P
Neurochem Res. 1982 Nov;7(11):1391-401. doi: 10.1007/BF00966068.
The effects of cations on taurine, hypotaurine and GABA uptake were studied in mouse brain slices under identical experimental conditions. The uptakes were all strictly sodium-dependent. The omission or excess of K+ inhibited similarly taurine, hypotaurine and GABA uptake. The effects of omission of Ca2+ or Mg2+ were less pronounced. In both normal-sodium and low-sodium media all uptakes were saturable, consisting of both low- and high-affinity transport components. The Km constants for both low- and high-affinity transport components of hypotaurine and GABA increased in low-sodium medium, suggesting that sodium ions are necessary for their attachment to possible carrier sites in plasma membranes. In the case of taurine, however, the translation rate rather than the affinity of carrier sites was affected in Na+-free media. More than two sodium ions may be involved in the transport of one hypotaurine and one GABA molecule, whereas the coupling ratio between sodium and taurine was at least three. In its cation dependence hypotaurine uptake thus resembled more GABA uptake than taurine uptake.
在相同实验条件下，研究了阳离子对小鼠脑片中山磺酸、次磺酸和γ-氨基丁酸（GABA）摄取的影响。这些摄取均严格依赖于钠离子。钾离子的缺失或过量对山磺酸、次磺酸和GABA摄取的抑制作用相似。钙离子或镁离子缺失的影响则不太明显。在正常钠浓度和低钠浓度培养基中，所有摄取均具有饱和性，由低亲和力和高亲和力转运成分组成。在低钠培养基中，次磺酸和GABA的低亲和力和高亲和力转运成分的米氏常数（Km）均升高，这表明钠离子对于它们附着于质膜上可能的载体位点是必需的。然而，在无钠培养基中，对于山磺酸而言，受影响的是转运速率而非载体位点的亲和力。一个次磺酸分子和一个GABA分子的转运可能涉及两个以上的钠离子，而钠与山磺酸的偶联比至少为3。因此，就其对阳离子的依赖性而言，次磺酸摄取更类似于GABA摄取，而非山磺酸摄取。
