碳水化合物(CHO)和亮氨酸(LEU)都具有促胰岛素特性,因此可以增强膳食蛋白质的蛋白质合成代谢能力,这是预防慢性阻塞性肺疾病(COPD)患者肌肉损失的重要营养素。还已知LEU独立于胰岛素激活蛋白质合成代谢信号通路。根据我们以前在COPD中的发现,我们假设CHO和LEU与蛋白质的单独和联合共同摄入可在相当程度上增强全身蛋白质合成代谢.
与高质量蛋白质共同摄入时,要解开CHO和/或游离LEU的蛋白质合成代谢作用,我们研究了10例中度至非常重度COPD和呼吸困难的患者(GOLD:II-IV,mMRC呼吸困难量表≥2),有肌肉损失的风险,和10个健康的年龄和性别相匹配的对照。有四次,在单盲随机交叉设计中,每个受试者摄入含有0.6g/kg无脂质量(ffm)水解酪蛋白的饮料,a)无附加物(蛋白质),b)0.3g/kgffmCHO(蛋白质+CHO),c)0.095g/kgffm亮氨酸(蛋白质+LEU),d)两种添加(蛋白质+CHO+LEU)。全身蛋白质分解(PB),蛋白质合成(PS),通过静脉灌注和连续输注L-[环-2H5]-苯丙氨酸和L-[13C9,15N]-酪氨酸来测量净蛋白质平衡(=PS-PB)。将L-[15N]-苯丙氨酸添加到蛋白质饮料中以测量内脏提取。
在两组中,全身PS,PB和净蛋白质平衡反应在四种蛋白质饮料之间相当,尽管补充LEU的饮料餐后血浆LEU浓度较高(P<0.05),与仅含蛋白质的饮料相比,补充CHO的饮料的胰岛素浓度更高(P<0.05)。
在高质量蛋白质中添加CHO和/或LEU不会进一步增加有肌肉损失风险的呼吸困难COPD患者或健康老年人的全身蛋白质合成代谢。
ClinicalTrials.gov;编号NCT01734473;URL:www.临床试验.gov.
Carbohydrates (CHO) and leucine (LEU) both have insulinotropic properties, and could therefore enhance the protein anabolic capacity of dietary proteins, which are important nutrients in preventing muscle loss in patients with Chronic Obstructive Pulmonary Disease (COPD). LEU is also known to activate protein anabolic signaling pathways independent of insulin. Based on our previous findings in COPD, we hypothesized that whole body protein anabolism is enhanced to a comparable extent by the separate and combined co-ingestion of CHO and LEU with protein.
To disentangle the protein anabolic effects of CHO and/or free LEU when co-ingested with a high-quality protein, we studied 10 patients with moderate to very severe COPD and dyspnea (GOLD: II-IV, mMRC dyspnea scale ≥ 2), at risk for muscle loss, and 10 healthy age- and gender-matched controls. On four occasions, in a single-blind randomized crossover design, each subject ingested a drink containing 0.6 g/kg fat-free mass (ffm) hydrolyzed casein protein with, a) no add-ons (protein), b) 0.3 g/kg ffm CHO (protein + CHO), c) 0.095 g/kg ffm leucine (protein + LEU), d) both add-ons (protein + CHO + LEU). Whole body protein breakdown (PB), protein synthesis (PS), and net protein balance (= PS - PB) were measured by IV primed and continuous infusion of L-[ring-2H5]-phenylalanine and L-[13C9,15N]-tyrosine. L-[15N]-phenylalanine was added to the protein drinks to measure splanchnic extraction.
In both groups, whole body PS, PB and net protein balance responses were comparable between the four protein drinks, despite higher postprandial plasma LEU concentrations for the LEU supplemented drinks (P < 0.05), and higher insulin concentrations for the CHO supplemented drinks as compared to the protein only drink (P < 0.05).
Adding CHO and/or LEU to a serving of high-quality protein does not further augment whole body protein anabolism in dyspneic COPD patients at risk for muscle loss or healthy older adults.
ClinicalTrials.gov; No. NCT01734473; URL: www.clinicaltrials.gov.