Citrulline Supplementation On Vascular Responsiveness and Function in Postmenopausal Women

L-Citrulline Supplementation to Improve Vascular Function and Responsiveness at Rest and During Exercise in Postmenopausal Women

The objective of this project is to provide evidence that L-Citrulline (L-CIT) supplementation can improve vascular function at rest and in response to exercise in postmenopausal women.

Study Overview

• Status: Completed
• Conditions: Menopause
• Intervention / Treatment: Dietary supplement: L-Citrulline; Dietary supplement: Placebo

Detailed Description

L-CIT is a non-essential amino acid that is a precursor to L-arginine, the substrate used to produce an important vasodilatory molecule called nitric oxide. The purpose of this study is to identify the effects of 6 grams of L-CIT for 4 weeks on vascular function (endothelial function, blood flow, muscle oxygenation, and blood pressure) at rest and in response to different stressors (cold pressor test, isometric and dynamic exercise).

• Study Type: Interventional
• Enrollment (Actual): 26
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Lubbock, Texas, United States, 79409
      • Texas Tech University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 46 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Postmenopausal (absence of menstruation > 1 year) between the ages of 50 - 79 years.
• Sedentary ( < 120 minutes of exercise/week)
• Resting systolic blood pressure < 150 mmHg and diastolic blood pressure < 90 mmHg
• Not participating as a subject in another study for at least 2 months prior to the study and for the duration of the study
• Willingness to abstain from food supplements 1 month prior to the start of the study and throughout the duration of the study

Exclusion Criteria:

• Body mass index ≥ 40
• Currently taking more than one vasoactive drug for blood pressure control
• Cardiometabolic diseases or other chronic diseases
• Taking hormone replacement therapy 3 months prior to the study
• Current or prior use of tobacco products
• More than a moderate intake of alcohol
• Use of medications and/or supplements that may affect outcome variables
• Musculoskeletal disorders that will prevent exercise performance

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: L-Citrulline; L-Citrulline: 6 grams/day	Dietary supplement: L-Citrulline; 4 weeks of L-Citrulline supplementation (6 grams/day)
Placebo Comparator: Placebo; Crystalline Cellulose	Dietary supplement: Placebo; 4 weeks of Placebo (crystalline cellulose)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microvascular endothelial function	Endothelial function will be assessed via reactive hyperemic index using the EndoPAT device.	4 weeks
Changes in brachial and aortic blood pressure responses via automated sphygmomanometry during metaboreflex activation	Brachial and aortic blood pressures (systolic and diastolic) will be assessed using an arm cuff during isometric handgrip exercise and postexercise muscle ischemia.	4 weeks
Changes in aortic hemodynamics using pulse wave analysis during metaboreflex activation	The speed and reflection pressures, both representing aortic hemodynamic parameters, will be assessed using radial applanation tonometry and a validated transfer function (AtCor Medical) during isometric handgrip exercise and postexercise muscle ischemia.	4 weeks
Blood flow during dynamic exercise	Blood flow will be measured using ultrasound in the superficial femoral and brachial artery during dynamic exercises superimposed with the cold pressor test.	4 weeks
Muscle oxygenation during dynamic exercise	Muscle oxygenation will be measured using near infrared spectroscopy during dynamic exercises superimposed with the cold pressor test.	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Serum nitric oxide levels	Serum levels of nitric oxide will be assessed.	4 weeks
Changes in brachial and aortic blood pressure responses via automated sphygmomanometry during dynamic plantarflexion exercise and handgrip combined with the cold pressor test	Brachial and aortic blood pressures (systolic and diastolic) will be assessed using an arm cuff during dynamic plantarflexion exercise and handgrip combined with the cold pressor test.	4 weeks
Changes in aortic hemodynamics using pulse wave analysis during dynamic plantarflexion exercise and handgrip combined with the cold pressor test	The speed and reflection pressures, both representing aortic hemodynamic parameters, will be assessed using radial applanation tonometry and a validated transfer function (AtCor Medical) during dynamic plantarflexion exercise and handgrip combined with the cold pressor test.	4 weeks

Collaborators and Investigators

• Sponsor: Texas Tech University
• Investigators: Principal Investigator: Arturo Figueroa, Texas Tech University

Study record dates

Study Major Dates

• Study Start (Actual): July 7, 2020
• Primary Completion (Actual): April 27, 2022
• Study Completion (Actual): April 27, 2022

Study Registration Dates

• First Submitted: October 24, 2022
• First Submitted That Met QC Criteria: October 26, 2022
• First Posted (Actual): October 31, 2022

Study Record Updates

• Last Update Posted (Actual): October 31, 2022
• Last Update Submitted That Met QC Criteria: October 26, 2022
• Last Verified: October 1, 2022

More Information

Terms related to this study

• Keywords: Endothelial function; Blood pressure; Blood flow
• Other Study ID Numbers: IRB2019-1197

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No