Gerencser G A, Hong S K
Biochim Biophys Acta. 1975 Sep 16;406(1):108-19. doi: 10.1016/0005-2736(75)90046-2.
This investigation was principally undertaken to test the ionic gradient hypothesis as applied to active p-aminohippurate uptake in the rabbit kidney cortical slice preparation. Efflux of p-aminohippurate from the slice was shown to be independent of external Na+ concentration. Transferring slices from a low sodium preincubation to a high sodium incubation medium containing p-aminohippurate increased intracellular concentrations of both Na+ and K+, and p-aminohippurate accumulation occurred. Transferring slices from a low sodium preincubation to a high sodium incubation medium containing ouabain and p-aminohippurate resulted in a net increase in intracellular Na+ concentration but no p-aminohippurate accumulation occurred. Different combinations of preincubation and incubation media gave a high to low array of intracellular Na+ concentrations and these directly reflected their respective p-aminohippurate uptake. These results suggest that the Na+ gradient hypothesis does not adequately explain the transport of organic acids in rabbit kidney. These results also suggest that Na+ possibly has an intracellular role through its stimulation of (Na+ + K+)-ATPase channeled to energizing the p-aminohippurate accumulative mechanism.
本研究主要旨在验证离子梯度假说，该假说应用于兔肾皮质切片制备中对氨基马尿酸的主动摄取。结果表明，对氨基马尿酸从切片中的流出与细胞外钠离子浓度无关。将切片从低钠预孵育转移至含有对氨基马尿酸的高钠孵育培养基中，会使细胞内钠离子和钾离子浓度均升高，并且对氨基马尿酸会发生蓄积。将切片从低钠预孵育转移至含有哇巴因和对氨基马尿酸的高钠孵育培养基中，会导致细胞内钠离子浓度净增加，但未发生对氨基马尿酸蓄积。预孵育和孵育培养基的不同组合产生了从高到低排列的细胞内钠离子浓度，且这些浓度直接反映了它们各自对氨基马尿酸的摄取情况。这些结果表明，钠离子梯度假说无法充分解释兔肾中有机酸的转运。这些结果还表明，钠离子可能通过刺激（钠 + 钾）-ATP酶在细胞内发挥作用，该酶可促使对氨基马尿酸蓄积机制获得能量。
