Brazy P, Chobanian M C
University of Wisconsin-Madison, USA.
Kidney Int Suppl. 1996 Dec;57:S30-4.
The addition of D-glucose to renal proximal tubule cells reduces phosphate transport and in conditions of limited phosphate availability reduces mitochondrial respiration, oxidative phosphorylation and ATP content, a phenomenon called the Crabtree effect. The present study examined the effects of D-glucose on cellular content of inorganic phosphate, phosphomonoesters, and ATP. These studies were performed in suspensions of canine proximal tubules using 31P NMR spectroscopy. When the extracellular medium contained 0.4 mM phosphate, addition of 8.3 mM D-glucose to the perifusion fluid significantly lowered cell content of inorganic phosphate (by 31%), phosphomonoesters (by 23%) and ATP (by 25%). Addition of a similar concentration of mannitol had no significant effect on these measured parameters. Removal of inorganic phosphate from the extracellular medium in the absence of glucose reduced the cellular content of inorganic phosphate by only 9%. These data indicate that a reduction in cellular phosphate occurs during the Crabtree effect. The glucose effect on cellular phosphates appears to be an inhibition of phosphate uptake and an enhancement of phosphate efflux. The data do not support the hypothesis that glucose induces an increase in sugar monophosphates.
向肾近端小管细胞中添加D - 葡萄糖会降低磷酸盐转运，并且在磷酸盐供应有限的情况下会降低线粒体呼吸、氧化磷酸化和ATP含量，这种现象称为克奈特效应。本研究检测了D - 葡萄糖对细胞内无机磷酸盐、磷酸单酯和ATP含量的影响。这些研究是在犬近端小管悬浮液中使用³¹P核磁共振波谱法进行的。当细胞外培养基含有0.4 mM磷酸盐时，向灌流液中添加8.3 mM D - 葡萄糖会显著降低细胞内无机磷酸盐含量（降低31%）、磷酸单酯含量（降低23%）和ATP含量（降低25%）。添加相似浓度的甘露醇对这些测量参数没有显著影响。在无葡萄糖的情况下从细胞外培养基中去除无机磷酸盐只会使细胞内无机磷酸盐含量降低9%。这些数据表明在克奈特效应期间细胞内磷酸盐会减少。葡萄糖对细胞内磷酸盐的影响似乎是抑制磷酸盐摄取并增强磷酸盐外流。这些数据不支持葡萄糖会导致单磷酸糖增加的假说。
