Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Clinical Center for Diabetes, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai, 200233, China.
Acta Diabetol. 2018 Mar;55(3):279-286. doi: 10.1007/s00592-017-1093-8. Epub 2018 Jan 9.
Our previous studies demonstrated that serum 1,5-anhydroglucitol (1,5-AG) levels increased slightly rather than declined after an acute glucose load. Therefore, the current study aims at exploring the transport and metabolic characteristics of 1,5-AG, as well as the effect of glucose on 1,5-AG transport.
K and V were determined to measure the affinity of glucose oxidase (GOD) and hexokinase (HK) for 1,5-AG and glucose. HepG2, C2C12, and primary mouse hepatocytes were incubated for 2 h with 1,5-AG at concentrations of 0, 80, and 160 μg/mL. Then, intracellular and extracellular concentrations of 1,5-AG were measured before and after washing with PBS to evaluate the transport and metabolic rates of 1,5-AG. In addition, the influence of an acute glucose load on the transport of 1,5-AG was studied.
The affinity of GOD and HK for 1,5-AG is 5 and 42.5% of that for glucose, respectively. Moreover, there is no de novo synthesis of 1,5-AG, and its metabolic rate is < 3%. After a 2 h incubation with additional 1,5-AG, the intracellular levels of 1,5-AG were 50-80% of extracellular levels. Moreover, intracellular 1,5-AG concentrations decreased rapidly and reached zero following the removal of 1,5-AG from the external medium. In addition, an acute glucose load can affect the dynamic balance of 1,5-AG, causing the intracellular 1,5-AG levels to decline significantly and the extracellular levels to increase slightly in HepG2 cells.
Unlike glucose, 1,5-AG is hard to be metabolized in vivo, and its transport is influenced by an acute glucose load in hepatocytes.
我们之前的研究表明，在急性葡萄糖负荷后，血清 1,5-脱水葡萄糖醇（1,5-AG）水平略有升高而不是下降。因此，本研究旨在探讨 1,5-AG 的转运和代谢特征，以及葡萄糖对 1,5-AG 转运的影响。
通过测定葡萄糖氧化酶（GOD）和己糖激酶（HK）对 1,5-AG 和葡萄糖的亲和力（K 和 V）来确定。用 0、80 和 160μg/mL 的浓度孵育 HepG2、C2C12 和原代小鼠肝细胞 2 小时，然后用 PBS 洗涤前后测量细胞内外 1,5-AG 的浓度，以评估 1,5-AG 的转运和代谢率。此外，还研究了急性葡萄糖负荷对 1,5-AG 转运的影响。
GOD 和 HK 对 1,5-AG 的亲和力分别为葡萄糖的 5%和 42.5%。此外，1,5-AG 没有从头合成，其代谢率<3%。在孵育 2 小时后添加额外的 1,5-AG，细胞内 1,5-AG 水平为细胞外水平的 50-80%。此外，细胞内 1,5-AG 浓度迅速下降，当从外部介质中去除 1,5-AG 时，浓度降为零。此外，急性葡萄糖负荷会影响 1,5-AG 的动态平衡，导致 HepG2 细胞内 1,5-AG 水平显著下降，细胞外水平略有增加。
与葡萄糖不同，1,5-AG 在体内不易代谢，其转运在肝细胞中受急性葡萄糖负荷的影响。
