Muscle Perfusion and Protein Metabolism in Elderly
Condition: Aging
Intervention: Aerobic Exercise; Sodium Nitroprusside; Amino Acid Drink
Intervention description: 45 minuties of treadmill walking was completed at 40% VO2 peak; Sodium Nitroprusside was given in a constant infusion for 180 minutes at a rate of 0.114 ug/kg/min; 7.5 gram Amino Acid drink
Intervention MeSH terms: Nitroprusside
Phase: Phase 1
Study type: Interventional
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Enrollment: 62.0
Sex: All
Minimum age: 18 Years
Maximum age: 85 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: metabolism; exercise; sodium nitroprusside

Summary:

      The purpose of this study was to examine the role skeletal muscle perfusion plays in
      mediating muscle protein synthesis in healthy older and younger individuals. The
      investigators hypothesized that normalization of muscle perfusion in older men and women via
      exercise or infusion of a vasodilator would enhance nutritive flow and skeletal muscle
      protein synthesis in the elderly similar to that of their younger counterparts.
    

Eligibility criteria:

        Inclusion Criteria:

        All inclusion criteria must be fulfilled throughout the study. At enrollment, subjects must
        fit the following criteria:

          1. Age: young 18-40 yrs; elderly 60-85 yrs.

          2. Availability of transportation (i.e., subjects must be able to provide their own
             transportation to UTMB).

          3. Ability to sign informed consent (score >24 on 30 item mini-mental status exam and no
             errors on assessment of judgment).

        Exclusion Criteria:

        None of the following exclusion criteria should be present at enrollment or throughout the
        study:

          1. Patients with limiting or unstable angina or who demonstrate cardiac abnormalities
             such as > 0.2 mV horizontal or downsloping ST segment depression, frequent arrhythmias
             (>10 PVC/min), or valvular disease.

          2. Any patient with atrial fibrillation, history of syncope, angina, or congestive heart
             failure.

          3. Patients with vascular disease, as determined by the presence of risk factors of
             peripheral atherosclerosis (i.e., hypertension, obesity, uncontrolled diabetes, and
             evidence of venous or arterial insufficiency upon palpation of femoral, popliteal, and
             pedal arteries).

          4. Peripheral vascular disease as determined by history or abnormal ankle-brachial index
             by Doppler (< 1.0).

          5. Any subject with blood pressure on three consecutive measurements taken at rest on
             separate occasions that has a systolic pressure >170 mm Hg or a diastolic blood
             pressure >100 mm Hg will be excluded. Subjects will not be included if they are taking
             blood pressure medication and have a blood pressure above these criteria.

          6. Any person HIV-seropositive, with active hepatitis, or any other immunosuppressive or
             autoimmune disease.

          7. Any patient taking beta blockers, vasodilators, angiotensin-converting enzyme
             inhibitors, calcium channel blockers, or alpha blockers.

          8. Any patient with uncontrolled metabolic diseases including any patient with liver or
             renal disease.

          9. Glucose intolerance: fasting plasma glucose concentration 110-126 mg/dL (6.1-7 mmol/L)
             and/or 2-h plasma glucose 140-200 mg/dL (7.8-11.1 mmol/L) during oral glucose
             tolerance test (OGTT).

         10. Currently in muscle strengthening program.

         11. Total knee replacement or moderate to severe degenerative joint disease of knees.

         12. Anemia (hemoglobin <13 g/dL in males or <12 g/dL in females).

         13. Any history of hypo- or hyper-coagulation disorders, including patients taking
             Coumadin or with a history of deep venous thrombosis (DVT) or pulmonary embolism (PE)
             at any point in their lifetimes.

         14. Currently taking aspirin and cannot stop for 7 days (i.e., medical indication for
             continued aspirin such as transient ischemic attacks).

         15. Presence of acute illness or metabolically unstable chronic illness.

         16. Heart disease requiring therapy or recent myocardial infarction (less than 1 year)

         17. Currently on weight-loss diet.

         18. Active cancer or in short-term remission (less than 3 years).

         19. Alcohol or drug abuse.

         20. History of >20 packs per year cigarette smoking.

         21. Recent (within 6 months) ingestion or injection or transdermal administration of
             anabolic steroids, corticosteroids, estrogens, or progestagens.

         22. History of falls (1 fall in the past year which required medical attention, or more
             than 2 falls/year regardless of severity).

         23. Allergy to iodides, penicillin or shellfish.

         24. Any subject with a know hypersensitivity to octafluoropropane.

         25. Any subject with a cardiac shunt.

         26. Any subject with chronic obstructive pulmonary disease (COPD).