2 Weeks of Citrulline Supplementation on Arterial Function in Postmenopausal Women With Elevated Blood Pressure or Hypertension

2 Weeks of L-Citrulline Supplementation Improves Arterial Function and Systolic Blood Pressure at Rest and During Exercise in Postmenopausal Women With Elevated Blood Pressure and Hypertension

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.

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.

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.