Dysfunction of Nutritive Blood Flow as a Determinant of Anabolic Resistance in Older People; The Role of Essential Amino Acids in Modulating Muscle Protein Metabolism; Bolus vs. Pulse Feeding Strategies and the Ability of Arginine to Rejuvenate Microvascular Responsiveness.
试验速览
- 阶段
- 不适用
- 入组人数
- 40
- 试验地点
- 2
- 主要终点
- Muscle Protein Synthesis (FSR, fractional synthetic rate, %/hr)
研究概览
简要总结
The investigators plan to measure changes in muscle protein metabolism in response to feeding, comparing between a single large essential amino acid (EAA) feed (the normal building blocks of protein) and the provision of the same dose in 4 smaller feeds at 45min intervals. The investigators will perform this study in healthy older (65-75y) and younger (18-28) men. The investigators will also explore how feeding affects muscle blood flow as this is important in the delivery of the nutrients we eat to the muscle where they are used.
The investigators plan to supplement the feed with arginine, a safe and widely found non-essential amino acid, to explore if this can improve muscle blood flow.
详细描述
We will provide a 15g mixed essential amino acid feed or 4 x 3.75g.
There is sexual dimorphism thus initially we will just recruit males. Powering calculations dictate n=8 in each group.
We will use well established stable isotope tracer techniques (with 13C6 Phenylalanine) to measure muscle protein synthesis and breakdown by Gas Chromatography - combustion - isotope ratio mass spectroscopy.
We will measure leg blood flow by phase shift Doppler and muscle microvascular flow by contrast enhanced ultrasound.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Double (Participant, Investigator)
入排标准
- 年龄范围
- 18 Years 至 75 Years（Adult, Older Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •age 65-75 or 18-28
排除标准
- •Beta blocker or steroid use
- •Established cerebrovascular, peripheral vascular or ischaemic heart disease.
结局指标
主要结局
Muscle Protein Synthesis (FSR, fractional synthetic rate, %/hr)
时间窗: Across 6hr study
We measure FSR when fasted and again 0-90, 90-180 and 180-240 post feed.
次要结局
- Muscle Protein Breakdown (MPB)(Across 6hr study)
- Muscle Microvascular Blood flow(Across a 6hr study)
- Whole leg blood flow(Across a 6hr study)