Stable Isotope Biochemistry Laboratory, SUERC, East Kilbride, Glasgow, UK.
Rapid Commun Mass Spectrom. 2011 Sep 15;25(17):2484-8. doi: 10.1002/rcm.5139.
The utilisation of carbohydrate sources under exercise conditions is of considerable importance in performance sports. Incorporation of optimal profiles of macronutrients can improve endurance performance in athletes. However, gaining an understanding of the metabolic partitioning under sustained exercise can be problematical and isotope labelling approaches can help quantify substrate utilisation. The utilisation of oral galactose was investigated using (13)C-galactose and measurement of plasma galactose and glucose enrichment by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS). As little as 100 μL plasma could readily be analysed with only minimal sample processing. Fucose was used as a chemical and isotopic internal standard for the quantitation of plasma galactose and glucose concentrations, and isotopic enrichment. The close elution of galactose and glucose required a correction routine to be implemented to allow the measurement, and correction, of plasma glucose δ(13)C, even in the presence of very highly enriched galactose. A Bland-Altman plot of glucose concentration measured by LC/IRMS against glucose measured by an enzymatic method showed good agreement between the methods. Data from seven trained cyclists, undergoing galactose supplementation before exercise, demonstrate that galactose is converted into glucose and is available for subsequent energy metabolism.
在运动条件下，碳水化合物来源的利用对于竞技体育具有重要意义。摄入最佳的宏量营养素谱可以提高运动员的耐力表现。然而，了解持续运动下的代谢分配可能具有挑战性，同位素标记方法可以帮助量化底物利用。使用 (13)C-半乳糖研究了口服半乳糖的利用情况，并通过液相色谱/同位素比质谱（LC/IRMS）测量血浆半乳糖和葡萄糖的富集。只需最小的样品处理，即可轻松分析少至 100μL 的血浆。岩藻糖被用作化学和同位素内标，用于定量血浆半乳糖和葡萄糖浓度以及同位素富集。由于半乳糖和葡萄糖的洗脱非常接近，因此需要实施校正程序，以便即使在半乳糖高度富集的情况下，也可以测量和校正血浆葡萄糖 δ(13)C。LC/IRMS 测量的葡萄糖浓度与酶法测量的葡萄糖浓度的 Bland-Altman 图显示了两种方法之间的良好一致性。对七名接受过运动前半乳糖补充的训练有素的自行车手进行的研究表明，半乳糖被转化为葡萄糖，可用于随后的能量代谢。
