Gruwel M L, Alves C, Schrader J
Department of Physiology I, Heinrich Heine University Düsseldorf, Germany.
Biochim Biophys Acta. 1994 Nov 10;1224(2):228-36. doi: 10.1016/0167-4889(94)90195-3.
23Na(+)-NMR was used to determine the intracellular mobility and cell membrane permeability of Na+ in porcine vascular endothelial cells. The cells were grown as monolayers onto microcarrier beads and perfused with a medium containing Dy(P3O10)2(7-) to shift the extracellular from the intracellular Na+ resonance. Using triple quantum coherence filtered NMR experiments and spin echoes, it was shown that not all intracellular Na+ ions are in the extreme narrowing limit. The triple quantum coherence filtered experiments resulted in an observed R2f = 2022 +/- 302 s-1 and R2s = 200 +/- 28 s-1. From spin-echo experiments we obtained R2f = 2200 +/- 355 s-1 and a R2s = 145 +/- 15 s-1. These values are similar to those found in other cell systems and indicate water-Na(+)-protein interactions. Using single quantum NMR, the Na+ permeability of the endothelial membrane was determined. To obtain the Na+ transcellular permeability coefficient the cells were treated with 50 microM ouabain in the perfusion medium. Ouabain inhibits the Na-K pump and caused the intracellular Na+ concentration to increase in time. The permeability coefficient was obtained from the time dependence of the intracellular Na+ concentration. Assuming a monolayer of rectangularly shaped cells, we obtained a value of P = 0.02.10-5 cm s-1.
利用23Na(+)-核磁共振技术测定猪血管内皮细胞中Na+的细胞内流动性和细胞膜通透性。将细胞以单层形式培养在微载体珠上，并用含有Dy(P3O10)2(7-)的培养基灌注，以使细胞外Na+共振与细胞内Na+共振发生偏移。通过三量子相干滤波核磁共振实验和自旋回波实验表明，并非所有细胞内的Na+离子都处于极窄线宽极限。三量子相干滤波实验得到的观测值R2f = 2022 +/- 302 s-1和R2s = 200 +/- 28 s-1。通过自旋回波实验，我们得到R2f = 2200 +/- 355 s-1和R2s = 145 +/- 15 s-1。这些值与其他细胞系统中的值相似，表明存在水-Na(+)-蛋白质相互作用。利用单量子核磁共振技术测定了内皮细胞膜的Na+通透性。为了获得Na+跨细胞通透性系数，在灌注培养基中用50 microM哇巴因处理细胞。哇巴因抑制Na-K泵，导致细胞内Na+浓度随时间增加。通透性系数由细胞内Na+浓度的时间依赖性获得。假设细胞为矩形单层，我们得到P = 0.02×10-5 cm s-1的值。
