Muscle Protein Synthesis
Conditions
Keywords
amino acid infusion, tracer methodology, muscle biopsy
Brief summary
Muscle tissue consists of proteins. These proteins are built up of a collection of smaller building blocks: amino acids. When protein is consumed, it gets digested and absorbed into the blood. The body can use these amino acids, by taking them up from thecirculation. By consuming sufficient protein through our diet, we ensure that the body is provided with enough amino acids to enable muscle protein building. Sufficient muscle protein synthesis is important for maintaining muscle function and strength. Previous research has shown that when 20 to 25g of protein is eaten, muscle protein synthesis is maximized. It is therefore recommended to eat 20g of protein per meal. However, it is currently unclear what happens to muscle protein synthesis rates if multiple meals are eaten. When multiple meals are consumed, amino acids appear in the circulation for prolonged period of time. Theoretically, when there are a high amino acid concentrations in the blood, muscle protein synthesis rates will increase. Contrary to this theory, a study more than 20 years ago showed otherwise. It was observed that muscle protein synthesis rates are only elevated for2 hours afterwhich they decrease again. This phenomenon was referred to as the muscle-full effect. Because this phenomenon is in contrast with more previous studies, the objective is to replicate that study. This is important so that nutritional advice for healthy, but also clinical populations in the future can be improved.
Interventions
OTHERContinuous intravenous stable isotope amino acid tracer infusion
During the single 12 h trial day, a primed continuous stable isotope infusion will run in order to assess muscle protein synthesis in the basal (4 h) and post-prandial (8 h) state.
OTHERAmino acid infusion
In order to assess muscle protein synthesis rates during continuous elevated plasma amino acid availability, the amino acid infusion solution Vamin®14 EF will be used. Vamin® 14EF contains 85g amino acids per liter and will be administered in the post-prandial period for 8 hours to ensure a constant rate of amino acid infusion over the full assessment period of the primary outcome measure.
Sponsors
Maastricht University Medical Center
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Cross-sectional, non-therapeutic, intervention study
Eligibility
Sex/Gender
MALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Male sex * Aged between 18 - 35 years * Healthy (assessed based on routine medical questionnaire) * BMI between 18.5 - 30 kg/m2
Exclusion criteria
A potential subject who meets any of the following criteria will be excluded from participation in this study: * Smoking * Involved in progressive exercise training * A history of neuromuscular problems * Use of anticoagulants * Recent (\<12 months) participation in amino acid tracer (L-\[ring-13C6\] phenylalanineand L-\[3,5-2H2\]-tyrosine) studies * Use of medication known to affect (muscle) protein metabolism (e.g. corticosteroids, non-steroidal anti-inflammatory drugs, acne medication) * Phenylketonuria * Diagnosed with or history of liver damage * Diagnosed with or history of severe kidney damage and/or malfunction * Diagnosed with inability to break down amino acids
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle protein synthesis during continuous elevated plasma amino acid avaialbility in healthy young males | 8 hours | The primary endpoint is muscle protein synthesis rates (in %/h) over the full assessment period (8 h) as determined with contemporary stable isotope tracer methodology combined with repeated blood and muscle sampling. Muscle protein synthesis are calculated using plasma as precursor pool and the tracer enrichment in the muscle (measured with UPLC and GC-IRMS). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Whole-body protein metabolism | 8 hours | synthesis, breakdown, oxidation, net balance (all expressed as μmol/kg/h). Based on amino acid concentrations in plasma and breath samples (measured with UPLC and GC-IRMS). |
| Whole-body protein kinetics | 8 hours | Including total rate of appearance, exogenous rate of appearance, endogenous rate of appearance, rate of disappearance based (all expressed as μmol/kg/min) on tracer plasma amino acid concentrations over time (measured with UPLC) |
| Basal muscle protein synthesis rates | 3 hours | Basal muscle protein synthesis rates (in %/h) will be assessed over a 3h period as determined with contemporary stable isotope tracer methodology combined with repeated blood and muscle sampling. Muscle protein synthesis are calculated using plasma as precursor pool and the tracer enrichment in the muscle biopsy (measured with UPLC and GC-IRMS). |
Countries
Netherlands
Contacts
Primary ContactLuc van Loon, PhD
Outcome results
None listed