myo-inositol transport and metabolism in fetal-bovine aortic endothelial cells.
myo-inositol transport and metabolism in fetal-bovine aortic endothelial cells.
复制标题
胎牛主动脉内皮细胞中的肌醇转运和代谢。
DOI：
10.1042/bj2950863
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Yandrasitz,JR
中科院分区：
文献类型：
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作者：
Berry,GT;Johanson,RA;Prantner,JE;States,B;Yandrasitz,JR
继代培养 7-10 天后，对汇合的胎牛主动脉内皮细胞中的肌醇转运系统进行了表征，此时肌醇水平以及肌醇摄取和掺入磷脂的速率已达到稳定状态。动力学分析表明，表观 Kt 为 31 microM 的高亲和力转运系统和 Vmax 均发生摄取。每毫克蛋白质 45 pmol/min，以及不饱和的低亲和力系统。根皮苷竞争性抑制摄取，Ki 为 50 microM；根皮素是一种非竞争性抑制剂，半最大抑制在 0.2 至 0.5 mM 之间。葡萄糖是一种弱竞争性抑制剂，Ki 为 37 mM；半乳糖未能抑制摄取。在 11 microM 肌醇时观察到初始吸收速率对 Na+ 的依赖性较弱。当使用含有225μM肌醇的胎牛血清(FBS)补充培养基时，细胞含有约200nmol肌醇/mg DNA。在添加了成人牛血清 (ABS) 的培养基中，其中含有 13 microM 肌醇，细胞中含有约 110 nmol/mg 的 DNA。对于在 FBS 和 ABS 中生长的细胞，11 microM 肌-[2-3]肌醇的转运分别为每毫克 DNA 18 和 125 pmol/分钟。动力学分析表明，对于在 FBS 中生长的细胞，Vmax。高亲和力系统的亲和力下降了64%，而Kt基本保持不变。细胞肌醇水平的增加与磷脂酰肌醇合成速率的增加无关。胎儿内皮细胞长时间暴露于接近胎儿高浓度而不是成人血液浓度较低的肌醇浓度后，细胞肌醇水平加倍，高亲和力转运发生下调。
The myo-inositol transport system in confluent fetal-bovine aortic endothelial cells was characterized after 7-10 days in subculture, at which time the myo-inositol levels and rates of myo-[2-3H]-inositol uptake and incorporation into phospholipid had reached steady state. Kinetic analysis indicated that the uptake occurred by both a high-affinity transport system with an apparent Kt of 31 microM and Vmax. of 45 pmol/min per mg of protein, and a non-saturable low-affinity system. Uptake was competitively inhibited by phlorhizin, with a Ki of 50 microM; phloretin was a non-competitive inhibitor, with half-maximal inhibition between 0.2 and 0.5 mM. Glucose was a weak competitive inhibitor, with a Ki of 37 mM; galactose failed to inhibit uptake. A weak dependence on Na+ for the initial rate of uptake was observed at 11 microM myo-inositol. When fetal-bovine-serum (FBS)-supplemented medium, which contained 225 microM myo-inositol, was used, the cells contained about 200 nmol of myo-inositol/mg of DNA. With adult-bovine-serum (ABS)-supplemented medium, which contained 13 microM myo-inositol, the cells contained about 110 nmol/mg of DNA. Transport of 11 microM myo-[2-3]inositol was 18 and 125 pmol/min per mg of DNA for cells grown in FBS and ABS respectively. Kinetic analysis showed that for the cells grown in FBS the Vmax. of the high-affinity system was decreased by 64%, whereas the Kt remained essentially unchanged. Increased cell myo-inositol levels were not associated with an increased rate of phosphatidylinositol synthesis. After prolonged exposure of fetal endothelial cells to a myo-inositol concentration which approximated to a high fetal as opposed to a low adult blood level, cell myo-inositol levels doubled and high-affinity transport underwent down-regulation.