使用2-脱氧葡萄糖定量测定心肌葡萄糖摄取背后的复杂性。

Complexities underlying the quantitative determination of myocardial glucose uptake with 2-deoxyglucose.

作者信息

Doenst T, Taegtmeyer H

机构信息

Division of Cardiology, University of Texas-Houston Medical School, Houston, TX, 77030, USA.

出版信息

J Mol Cell Cardiol. 1998 Aug;30(8):1595-604. doi: 10.1006/jmcc.1998.0725.

DOI:10.1006/jmcc.1998.0725

PMID:9737945

Abstract

The quantitative determination of glucose uptake by using 2-deoxy-D-glucose (2-DG) is based on the assumption that 2-deoxyglucose-6-phosphate (2-DG6P) cannot be further metabolized and requires the lumped constant (LC) to equate the kinetic differences in uptake between 2-DG and glucose. We tested whether insulin or epinephrine affect the LC, and quantitated the incorporation of 2-DG6P into glycogen in the isolated working rat heart. Hearts were perfused for 35 min at near physiological workload with Krebs-Henseleit buffer containing glucose (5 mmol/l) plus oleate (0.4 mmol/l, Group 1) with either insulin (1 mU/ml, Group 2), or epinephrine (1 micromol/l, Group 3). In all groups [2-3H] glucose and [U-14C]2-DG (10 microCi each) were present in the perfusate for the first 30 min. In order to estimate the quantitative relationship of glucose and 2-DG uptake and glycogen synthesis from glucose and 2-DG, we perfused hearts with equimolar amounts of glucose and 2-DG (5 mmol each) and either [18F]2-deoxy-2-fluoroglucose plus [2-3H]glucose or [U-14C]glucose plus [1,2-3H]2-DG as tracers. All hearts were freeze-clamped for determination of 2-DG accumulation, glycogen, and tracer activity in glycogen. Glucose and 2-DG uptake were similar in the absence of insulin (LC 1.27+/-0.09). In the presence of insulin, 2-DG underestimated glucose uptake (LC 0.61+/-0.02). Epinephrine did not affect the tracer/tracee ratio (LC 1.31+/-0.09). Incorporation of [U-14C]2-DG into glycogen occurred in all groups (Group 15.38+/-0. 65%, Group 25.72+/-0.59%, Group 32.70+/-0.16% of total tracer uptake.) When equimolar amounts of glucose and 2-DG were present, 2-DG uptake, measured by dynamic assessment of FDG accumulation, significantly decreased over 30 min while glucose uptake remained unchanged. The hearts perfused with [U-14C]glucose and [1,2-3H]2-DG synthesized 39.5+/-7.1 micromol glycogen/g dry/30 min. 2-DG contributed 4.2+/-1.4%. We conclude that insulin and epinephrine have differential effects on the LC, and 2-DG6P is a substrate for glycogen synthesis.

摘要

使用2-脱氧-D-葡萄糖（2-DG）定量测定葡萄糖摄取基于这样的假设，即6-磷酸-2-脱氧葡萄糖（2-DG6P）不能进一步代谢，并且需要集总常数（LC）来平衡2-DG与葡萄糖摄取的动力学差异。我们测试了胰岛素或肾上腺素是否会影响LC，并对2-DG6P掺入离体工作大鼠心脏糖原中的情况进行了定量。在接近生理工作负荷下，用含葡萄糖（5 mmol/L）加油酸（0.4 mmol/L，第1组）的Krebs-Henseleit缓冲液灌注心脏35分钟，其中第2组加入胰岛素（1 mU/ml），第3组加入肾上腺素（1 μmol/L）。在所有组中，前30分钟灌注液中存在[2-³H]葡萄糖和[U-¹⁴C]2-DG（各10 μCi）。为了估计葡萄糖和2-DG摄取以及葡萄糖和2-DG糖原合成的定量关系，我们用等摩尔量的葡萄糖和2-DG（各5 mmol）以及[¹⁸F]2-脱氧-2-氟葡萄糖加[2-³H]葡萄糖或[U-¹⁴C]葡萄糖加[1,2-³H]2-DG作为示踪剂灌注心脏。所有心脏均经冷冻钳夹以测定2-DG蓄积、糖原以及糖原中的示踪剂活性。在无胰岛素时，葡萄糖和2-DG摄取相似（LC 1.27±0.09）。存在胰岛素时，2-DG低估了葡萄糖摄取（LC 0.61±0.02）。肾上腺素不影响示踪剂/被示踪物比值（LC 1.31±0.09）。所有组中均发生了[U-¹⁴C]2-DG掺入糖原的情况（第1组占总示踪剂摄取的15.38±0.65%，第2组为5.72±0.59%，第3组为2.70±0.16%）。当存在等摩尔量的葡萄糖和2-DG时，通过动态评估FDG蓄积测定的2-DG摄取在30分钟内显著下降，而葡萄糖摄取保持不变。用[U-¹⁴C]葡萄糖和[1,2-³H]2-DG灌注的心脏合成糖原的量为39.5±7.1 μmol/g干重/30分钟。2-DG的贡献为4.2±1.4%。我们得出结论，胰岛素和肾上腺素对LC有不同影响，并且2-DG6P是糖原合成的底物。