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Completed

NCT Number: NCT06025383

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

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Key information

Conditions

Menopause Cardiovascular Diseases Hypertension Vascular Diseases

Age range

50 year–70 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Texas Tech University

Lubbock, Texas, 79409, United States

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

L-citrulline

Dietary Supplement

2 weeks of L-Citrulline supplementation (6 grams/day)

Placebo

Dietary Supplement

2 weeks of microcrystalline cellulose supplementation (8 capsules/day)

Primary outcomes

  1. Macrovascular endothelial function at rest

    Time frame: 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.

  2. Microvascular endothelial function at rest

    Time frame: 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.

  3. Microvascular endothelial function at rest

    Time frame: 2 weeks of each intervention

    Endothelial function will be assessed using forearm muscle oxygen saturation (near-infrared spectroscopy) during reactive hyperemia before and after 2 weeks of each supplementation.

  4. Brachial artery blood flow at rest and during rhythmic handgrip exercise with and without lower-body negative pressure

    Time frame: 2 weeks of each intervention

    Blood flow will be measured via Doppler ultrasound before and after 2 weeks of each intervention.

  5. Forearm muscle oxygenation at rest and during rhythmic handgrip exercise with and without lower-body negative pressure

    Time frame: 2 weeks of each intervention

    Muscle oxygen saturation will be measured via near-infrared spectroscopy before and after 2 weeks of each intervention.

Secondary outcomes

  1. Beat-to-beat blood pressure at rest and during rhythmic handgrip exercise with and without lower-body negative pressure

    Time frame: 2 weeks of each intervention

    Blood pressure will be measured via a finger cuff (finometer) before and after 2 weeks of each intervention.

  2. Aortic hemodynamics at rest and during rhythmic handgrip exercise with and without lower body negative pressure

    Time frame: 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.

  3. Stroke volume at rest and during rhythmic handgrip exercise with and without lower body negative pressure

    Time frame: 2 weeks of each intervention

    Stroke volume will be assessed via impedance cardiography before and after 2 weeks of each intervention.

  4. Heart rate at rest and during rhythmic handgrip exercise with and without lower body negative pressure

    Time frame: 2 weeks of each intervention

    Heart rate will be assessed via impedance cardiography before and after 2 weeks of each intervention.

  5. Systemic vascular resistance at rest and during rhythmic handgrip exercise with and without lower body negative pressure

    Time frame: 2 weeks of each intervention

    Systemic vascular resistance will be assessed via impedance cardiography before and after 2 weeks of each intervention.

  6. Central and peripheral arterial stiffness at rest

    Time frame: 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.

  7. Forearm muscle strength

    Time frame: 2 weeks of each intervention

    Maximal forearm muscle strength will be measured using a handgrip dynamometer before and after 2 weeks of each intervention.

  8. L-arginine levels

    Time frame: 2 weeks of each intervention

    Serum levels of l-arginine will be assessed before and after 2 weeks of each intervention.

  9. Nitric oxide levels

    Time frame: 2 weeks of each intervention

    Serum levels of nitric oxide will be assessed before and after 2 weeks of each intervention.

  10. L-citrulline levels

    Time frame: 2 weeks of each intervention

    Serum levels of l-citrulline will be assessed before and after 2 weeks of each intervention.

  11. L-ornithine levels

    Time frame: 2 weeks of each intervention

    Serum levels of l-ornithine will be assessed before and after 2 weeks of each intervention.

Sponsors and collaborators

Lead sponsor

Texas Tech University

Other

Registry information

Official study title

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

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Sep 6, 2023
Registry last updated
May 15, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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