Loss of muscle mass in healthy aging (sarcopenia)
Conditions
Interventions
The intervention consist of a single test day during which the subjects will receive a drink containing 20 gram intrinsically labeled casein followed by local administration of insulin (0.3 mU/min/100
Sponsors
Maastricht University
Eligibility
Inclusion criteria
Inclusion criteria: 1. Healthy untrained men; 2. Age 70-85 years or age 18-30 years; 3. BMI < 30 kg∙m2, with a stable body weight over the last 3 months.
Exclusion criteria
Exclusion criteria: 1. Cardiac abnormalities; 2. Coagulation disorders; 3. Vascular diseases; 4. Obesity (BMI > 30 kg∙m2); 5. Diabetes mellitus type 1 and type 2; 6. Glucose intolerance; 7. HbA1c > 7.0%; 8. Diagnosed impaired renal or liver function; 9. Smoking; 10. All co-morbidities interacting with mobility and muscle metabolism of the lower limbs (e.g. arthrosis, arthritis, spasticity/rigidity, all neurological disorders and paralysis); 11. Cancer; 12. Hypertension (according to WHO criteria); 13. Acute or chronic pulmonary diseases; 14. Allergy for lidocain or iodine; 15. Use of NSAIDs and acetylsalicylic acid; 16. Patients suffering from PKU (Phenylketonuria); 17. Infectious disease; 18. Participation in any regular exercise program; 19. Unstable body weight over the last 3 months.
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The main study endpoint is the muscle protein synthesis rate, expressed as fractional synthetic rate (FSR). In order to determine the FSR, the following parameters will be measured in blood and muscle tissue: 1. Plasma and muscle free phenylalanine concentration (expressed as μmol/L); 2. Plasma enrichment of L-[ ring-2H5]phenylalanine (expressed as mole percent excess (MPE)); 3. Muscle protein bound enrichment of L-[ ring-2H5]phenylalanine (expressed as MPE); 4. L-[ ring-2H5]phenylalanine enrichment of the muscle free amino acid pool (expressed as MPE). | — |
Secondary
| Measure | Time frame |
|---|---|
| Secondary endpoints include whole body protein turnover, protein digestion and absorption kinetics and microvascular perfusion. The following parameters will be calculated: 1. Exogenous phenylalanine rate of appearance and plasma availability of phenylalanine; 2. Total rate of phenylalanine appearance and disappearance (= protein turnover); 3. Endogenous phenylalanine rate of appearance (=protein breakdown); 4. Femoral blood flow using Doppler ultrasound expressed as L/min; 5. Leg blood flow using ICG dye dilution expressed as mL/min/100mL leg; 6. Sublingual microvascular perfusion measured using the SDF camera expressed as: Proportion of perfused vessels (PPV; %), perfused vessel density (PVD; n/mm) and Microcirculatory flow index (MFI). | — |
Contacts
Public ContactB. Groen
Outcome results
None listed