Hypertension, Menopause
Conditions
Keywords
Endothelial function, Blood flow, Blood pressure, Functional sympatholysis
Brief summary
The objective of this project is to elucidate the effect of L-Citrulline (L-CIT) supplementation on vascular function at rest and during rhythmic handgrip exercise and functional sympatholysis via lower-body negative pressure in postmenopausal women with elevated blood pressure and hypertension.
Detailed description
Using a double-blind, randomized, placebo-controlled, and crossover design, overweight or obese postmenopausal women with elevated blood pressure (BP) or hypertension will receive CIT (6 grams/day) or placebo for 2 weeks, separated by a two-week washout period. There will be a total of 5 laboratory visits. The 1st visit will take approximately 1 hour. The 2nd - 5th visits will take about 2 hours and 15 minutes. Visit 1 will be a screening visit, visits 2 and 4 will be considered baseline visits, and visits 3 and 5 will be following the participants' two weeks of supplementation. Arterial stiffness (carotid-femoral and femoral-dorsalis pedis pulse wave velocity) and endothelial function will be assessed at rest. Additionally, brachial artery blood flow, forearm muscle oxygenation, cardiovascular hemodynamics (stroke volume, cardiac output, systemic vascular resistance), and BP will be assessed at rest, during 6 minutes of rhythmic handgrip exercise at 30% of a predetermined maximal voluntary contraction, and 2 minutes of superimposed lower body negative pressure to increase sympathetic activity.
Interventions
DIETARY_SUPPLEMENTL-Citrulline
2 weeks of L-Citrulline supplementation (6 grams/day)
DIETARY_SUPPLEMENTPlacebo
2 weeks of microcrystalline cellulose supplementation (8 capsules/day)
Sponsors
Texas Tech University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Intervention model description
Cross-Over Assignment Double (Participant, Investigator) randomized, double-blind, placebo-controlled, cross-over study design
Eligibility
Sex/Gender
FEMALE
Age
50 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
* Postmenopausal women (defined as the absence of menstruation for at least 1 year). * Resting systolic blood pressure 120-150 mmHg. * Between the ages of 50 - 70 years. * Sedentary (\< 120 minutes of exercise/week). * Body mass index of 25 - 39.9 kg/m2. * Fasting glucose \< 126 mg/dL and HbA1c \< 6.5%.
Exclusion criteria
* Body mass index ≥ 40 or \< 25 kg/m2. * Systolic blood pressure \> 150 mmHg. * Taking more than two antihypertensive medications. * Cardiovascular diseases, type I/II diabetes, musculoskeletal disorders, or cancer. * Changes in hypertensive medication in the past three months. * Began or changed hormone replacement therapy in the past 6 months. * Current smoker. * Heavy drinking (\> 7 alcoholic drinks/week). * Participants on beta-blockers or other vasodilatory supplements (nitrates). * Incorporated in a weight loss program and/or aerobic or resistance training program.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Macrovascular endothelial function at rest | 2 weeks of each intervention | Endothelial function will be assessed via brachial artery flow-mediated vasodilation (ultrasonography) during reactive hyperemia at baseline and after 2 weeks of each supplementation. |
| Microvascular endothelial function at rest | 2 weeks of each intervention | Endothelial function will be assessed via peripheral arterial tonometry (endoPAT) during reactive hyperemia at baseline and after 2 weeks of each supplementation. |
| Brachial artery blood flow at rest and during rhythmic handgrip exercise with and without lower-body negative pressure | 2 weeks of each intervention | Blood flow will be measured via Doppler ultrasound before and after 2 weeks of each intervention. |
| Forearm muscle oxygenation at rest and during rhythmic handgrip exercise with and without lower-body negative pressure | 2 weeks of each intervention | Muscle oxygen saturation will be measured via near-infrared spectroscopy before and after 2 weeks of each intervention. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Systemic vascular resistance at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 weeks of each intervention | Systemic vascular resistance will be assessed via impedance cardiography before and after 2 weeks of each intervention. |
| Central and peripheral arterial stiffness at rest | 2 weeks of each intervention | Carotid-femoral and femoral-dorsalis pedis pulse wave velocity will be measured using arterial applanation tonometry before and after 2 weeks of each intervention. |
| Forearm muscle strength | 2 weeks of each intervention | Maximal forearm muscle strength will be measured using a handgrip dynamometer before and after 2 weeks of each intervention. |
| Beat-to-beat blood pressure at rest and during rhythmic handgrip exercise with and without lower-body negative pressure | 2 weeks of each intervention | Blood pressure will be measured via a finger cuff (finometer) before and after 2 weeks of each intervention. |
| Nitric oxide levels | 2 weeks of each intervention | Serum levels of nitric oxide will be assessed before and after 2 weeks of each intervention. |
| L-citrulline levels | 2 weeks of each intervention | Serum levels of l-citrulline will be assessed before and after 2 weeks of each intervention. |
| L-ornithine levels | 2 weeks of each intervention | Serum levels of l-ornithine will be assessed before and after 2 weeks of each intervention. |
| L-arginine levels | 2 weeks of each intervention | Serum levels of l-arginine will be assessed before and after 2 weeks of each intervention. |
| Aortic hemodynamics at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 weeks of each intervention | Aortic blood pressure and pressure waves will be assessed using radial applanation tonometry before and after 2 weeks of each intervention. |
| Stroke volume at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 weeks of each intervention | Stroke volume will be assessed via impedance cardiography before and after 2 weeks of each intervention. |
| Heart rate at rest and during rhythmic handgrip exercise with and without lower body negative pressure | 2 weeks of each intervention | Heart rate will be assessed via impedance cardiography before and after 2 weeks of each intervention. |
Countries
United States
Outcome results
None listed