Madsen K L, Porter V M, Fedorak R N
Department of Medicine, University of Alberta, Edmonton, Canada.
J Cell Physiol. 1994 Mar;158(3):459-66. doi: 10.1002/jcp.1041580310.
The effect of vanadate pentoxide on apical sodium-dependent glucose transport in LLC-PK1 epithelia was examined. Epithelia grown in the presence or absence of 1 microM vanadate formed confluent monolayers and exhibited no differences in DNA, protein, or ultrastructure. Vanadate-supplemented epithelia demonstrated a lower steady-state alpha-methyl-D-glucopyranoside (AMG) concentrating capacity and a twofold reduction in apical AMG uptake Jmax. This decreased AMG transport occurred as a consequence of a reduction in the number of transport carriers and was not associated with a change in the sodium electrochemical gradient. The vanadate-induced reduction in apical glucose carrier functional activity and expression was accompanied by a stimulation of intracellular glycolytic flux activity, as evidenced by increased glucose consumption, lactate production, PFK-1 activity, and intracellular ATP. There was no difference in intracellular cAMP levels between vanadate-supplemented and non-supplemented epithelia. These results demonstrate an association between stimulation of glycolytic pathway activity and an adaptive response in the form of a reduction in the function and expression of the sodium-dependent apical glucose transporter in LLC-PK1 epithelia.
研究了五氧化二钒对LLC-PK1上皮细胞顶端钠依赖性葡萄糖转运的影响。在存在或不存在1微摩尔钒酸盐的情况下生长的上皮细胞形成汇合单层，在DNA、蛋白质或超微结构方面没有差异。补充钒酸盐的上皮细胞表现出较低的稳态α-甲基-D-吡喃葡萄糖苷（AMG）浓缩能力，顶端AMG摄取Jmax降低了两倍。这种AMG转运减少是由于转运载体数量减少所致，与钠电化学梯度的变化无关。钒酸盐诱导的顶端葡萄糖载体功能活性和表达降低伴随着细胞内糖酵解通量活性的刺激，这表现为葡萄糖消耗增加、乳酸产生增加、PFK-1活性增加和细胞内ATP增加。补充钒酸盐的上皮细胞和未补充钒酸盐的上皮细胞之间细胞内cAMP水平没有差异。这些结果表明，糖酵解途径活性的刺激与LLC-PK1上皮细胞中钠依赖性顶端葡萄糖转运体功能和表达降低形式的适应性反应之间存在关联。
