Wesslén N, Hellman B
Department of Medical Cell Biology, University of Uppsala, Sweden.
Acta Physiol Scand. 1988 May;133(1):11-7. doi: 10.1111/j.1748-1716.1988.tb08375.x.
The mechanisms for glucose regulation of the sodium content of the pancreatic beta-cells were examined using aggregates of cells prepared from ob/ob-mice of a local colony. Exposure to glucose rapidly resulted in a protracted lowering of the sodium content as estimated with integrating flame photometry. Sodium became decreased after addition of 1 mmol l-1 glucose, and this effect was maximal with 5 mmol l-1 of the sugar. The effects of low glucose concentrations on the sodium content could not be mimicked by the poorly metabolized 3-o-methyl-D-glucose, and it disappeared in the presence of the metabolic inhibitor antimycin A. The significance of the Na/K pump for maintaining low sodium was illustrated by a substantial increase of the element in the presence of ouabain. However, there was no indication that glucose-induced lowering of sodium reflected activation of this pump when measuring the ouabain-sensitive uptake of 86Rb+. Neither bumetanide nor the bromo derivatives of cyclic AMP or cyclic GMP modified the glucose action on the sodium content. In evaluating whether the effect of glucose was mimicked by other inhibitors of the K+ permeability it was observed that 100 mumol l-1 quinine, but not tolbutamide, decreased sodium. It is concluded that the beta-cell is exceptional among excitable cells in responding to its natural physiological stimulant (glucose) by reduction of sodium. Acting in this way glucose facilitates the removal of Ca2+ from the cytoplasm.
利用本地群体中ob/ob小鼠制备的细胞聚集体，研究了胰腺β细胞钠含量的葡萄糖调节机制。通过积分火焰光度法估计，暴露于葡萄糖会迅速导致钠含量长时间降低。加入1 mmol/L葡萄糖后钠含量降低，5 mmol/L的糖时这种效应最大。代谢不良的3 - o - 甲基 - D - 葡萄糖无法模拟低葡萄糖浓度对钠含量的影响，且在代谢抑制剂抗霉素A存在时这种影响消失。哇巴因存在时该元素大幅增加，说明了钠钾泵对维持低钠水平的重要性。然而，在测量86Rb +的哇巴因敏感摄取时，没有迹象表明葡萄糖诱导的钠降低反映了该泵的激活。布美他尼以及环磷酸腺苷或环磷酸鸟苷的溴代衍生物均未改变葡萄糖对钠含量的作用。在评估葡萄糖的作用是否被其他钾离子通透性抑制剂模拟时，观察到100 μmol/L奎宁可降低钠含量，而甲苯磺丁脲则不能。得出的结论是，β细胞在可兴奋细胞中是特殊的，它通过降低钠含量来响应其天然生理刺激物（葡萄糖）。以这种方式作用时，葡萄糖有助于从细胞质中去除Ca2 +。
