Oude Elferink R P, Ottenhoff R, Liefting W G, Schoemaker B, Groen A K, Jansen P L
Division of Gastrointestinal and Liver Diseases, Academic Medical Centre, Amsterdam, The Netherlands.
Am J Physiol. 1990 May;258(5 Pt 1):G699-706. doi: 10.1152/ajpgi.1990.258.5.G699.
The driving force for efflux of dinitrophenyl-glutathione (GS-DNP) and oxidized glutathione (GSSG) from freshly isolated rat hepatocytes was studied. Incubation of hepatocytes in Krebs with increasing K+ concentrations (equivalently replaced for Na+) or in Krebs with 3 mM ouabain led to a partial or complete dissipation of the plasma membrane potential, as measured by the equilibrium distribution of 36Cl-. This had no effect on the initial efflux rate of GSSG and GS-DNP. On the other hand, partial depletion of the cellular ATP content via different independent mechanisms significantly reduced the initial efflux rate of these compounds. Titration of the cellular ATP content by incubation of the cells with different concentrations of atractyloside revealed a linear relation between the cellular ATP content and the initial efflux rate of GS-DNP. The efflux of GS-DNP was also studied in hepatocytes from mutant rats with hepatobiliary transport defect (TR- rats). These rats have a hereditary canalicular secretion defect for a number of organic anions including GS-DNP. As we have shown previously, the efflux of GS-DNP from TR- rat hepatocytes is significantly slower than from normal hepatocytes (J. Clin. Invest. 84: 476-483, 1989). Depletion of the cellular ATP content in these cells had no significant effect on the residual efflux of GS-DNP. From these studies, we conclude that an ATP-dependent transport system for oxidized glutathione and glutathione conjugates is involved in the biliary transport of these compounds. The possible relation of this transport system with that described in other cell types and tissues, like erythrocytes and heart sarcolemma, is discussed.
研究了从新鲜分离的大鼠肝细胞中排出二硝基苯基谷胱甘肽（GS-DNP）和氧化型谷胱甘肽（GSSG）的驱动力。用增加的K⁺浓度（等量替代Na⁺）在Krebs液中孵育肝细胞，或在含3 mM哇巴因的Krebs液中孵育肝细胞，导致质膜电位部分或完全消失，这是通过³⁶Cl⁻的平衡分布来测量的。这对GSSG和GS-DNP的初始外排速率没有影响。另一方面，通过不同的独立机制部分耗尽细胞内ATP含量，显著降低了这些化合物的初始外排速率。用不同浓度的苍术苷孵育细胞来滴定细胞内ATP含量，结果显示细胞内ATP含量与GS-DNP的初始外排速率之间呈线性关系。还研究了患有肝胆转运缺陷的突变大鼠（TR-大鼠）肝细胞中GS-DNP的外排情况。这些大鼠对包括GS-DNP在内的多种有机阴离子存在遗传性胆小管分泌缺陷。正如我们之前所表明的，TR-大鼠肝细胞中GS-DNP的外排明显比正常肝细胞慢（《临床研究杂志》84: 476 - 483, 1989）。这些细胞中细胞内ATP含量的耗尽对GS-DNP的残余外排没有显著影响。从这些研究中，我们得出结论，一种依赖ATP的氧化型谷胱甘肽和谷胱甘肽共轭物转运系统参与了这些化合物的胆汁转运。讨论了该转运系统与其他细胞类型和组织（如红细胞和心肌肌膜）中所描述的转运系统之间可能的关系。
