Department of Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Baylor College of Medicine, Houston, Texas, USA.
J Appl Physiol (1985). 2012 Jan;112(1):42-7. doi: 10.1152/japplphysiol.00599.2011. Epub 2011 Oct 20.
The mechanisms leading to weight loss in patients with chronic obstructive pulmonary disease (COPD) are poorly understood but may involve alterations in macronutrient metabolism. Changes in muscle oxidative capacity and lactate production during exercise suggest glucose metabolism may be altered in COPD subjects. The objective of this study was to determine differences in the rates of glucose production and clearance, the rate of glycolysis (pyruvate production), and oxidative and nonoxidative pyruvate disposal in subjects with severe COPD compared with healthy controls. The in vivo rates of glucose production and clearance were measured in 14 stable outpatients with severe COPD (seven with low and seven with preserved body mass indexes) and 7 healthy controls using an intravenous infusion of [(2)H(2)]glucose. Additionally, pyruvate production and oxidative and non-oxidative pyruvate disposal were measured using intravenous infusions of [(13)C]bicarbonate and [(13)C]pyruvate. Endogenous glucose flux and glucose clearance were significantly faster in the combined COPD subjects (P = 0.002 and P < 0.001, respectively). This difference remained significant when COPD subjects were separated by body mass index. Pyruvate flux and oxidation were significantly higher in the combined COPD subjects than controls (P = 0.02 for both), but there was no difference in nonoxidative pyruvate disposal or plasma lactate concentrations between the two groups. In subjects with severe COPD, there are alterations in glucose metabolism leading to increased glucose production and faster glucose metabolism by glycolysis and oxidation compared with controls. However, no difference in glucose conversion to lactate via pyruvate reduction is observed.
导致慢性阻塞性肺疾病（COPD）患者体重减轻的机制尚不清楚，但可能涉及到宏量营养素代谢的改变。运动过程中肌肉氧化能力和乳酸生成的变化表明 COPD 患者的葡萄糖代谢可能发生改变。本研究的目的是确定与健康对照组相比，严重 COPD 患者的葡萄糖生成和清除率、糖酵解（丙酮酸生成）率以及氧化和非氧化丙酮酸处置率的差异。使用静脉输注 [(2)H(2)]葡萄糖，在 14 名稳定的严重 COPD 门诊患者（7 名低体重指数和 7 名体重指数正常）和 7 名健康对照者中测量体内葡萄糖生成和清除率。此外，使用静脉输注 [(13)C]碳酸氢盐和 [(13)C]丙酮酸测量丙酮酸生成和氧化和非氧化丙酮酸处置。在合并的 COPD 患者中，内源性葡萄糖通量和葡萄糖清除率明显加快（P = 0.002 和 P < 0.001）。当按体重指数将 COPD 患者分开时，这种差异仍然显著。与对照组相比，合并的 COPD 患者的丙酮酸通量和氧化明显更高（两者均为 P = 0.02），但两组之间的非氧化丙酮酸处置或血浆乳酸浓度没有差异。在严重 COPD 患者中，葡萄糖代谢发生改变，导致与对照组相比葡萄糖生成增加，糖酵解和氧化的葡萄糖代谢更快。然而，通过丙酮酸还原将葡萄糖转化为乳酸没有观察到差异。
