Old Age (Focus; Not a Recognized Condition)
Conditions
Keywords
old age, sarcopenia, essential amino acid, arginine, contrast enhanced ultrasound, muscle microcirculation, muscle protein synthesis
Brief summary
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.
Detailed description
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.
Interventions
DIETARY_SUPPLEMENT15g EAA bolus
Oral; in aqueous solution
DIETARY_SUPPLEMENT4 x 3.75g Mixed EAA Pulses
Oral; in aqueous solution
DIETARY_SUPPLEMENT15g EAA Bolus supplemented with 3g Arginine
Oral; in aqueous solution
Sponsors
University of Nottingham
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
MALE
Age
18 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
* age 65-75 or 18-28
Exclusion criteria
* BMI \>30 * Diabetes * Beta blocker or steroid use * Established cerebrovascular, peripheral vascular or ischaemic heart disease.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle Protein Synthesis (FSR, fractional synthetic rate, %/hr) | Across 6hr study | We measure FSR when fasted and again 0-90, 90-180 and 180-240 post feed. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Muscle Protein Breakdown (MPB) | Across 6hr study | MBP is measured during fasting and 0-90, 90-180 and 180-240mins post feed. |
| Whole leg blood flow | Across a 6hr study | We measure common femoral blood flow by doppler ultrasound when fasted and again 0-90, 90-180 and 180-240 post feed. |
| Muscle Microvascular Blood flow | Across a 6hr study | We measure muscle microvascular flow using contrast enhanced ultrasound when fasted and again 0-90, 90-180 and 180-240 post feed. |
Countries
United Kingdom
Outcome results
None listed