NCT03981640

Neural Control of Kidney Blood Flow During Exercise in African American Adults

Neurovascular Control of Renal Blood Flow During Exercise in African American Adults

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 32 (estimated)
• Sponsor: University of Massachusetts, Boston · Academic / Other
• Sex: All
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

The goal of this clinical trials is to learn if healthy young African American (AA) adults have a larger change in their kidney blood flow during exercise compared to White (W) adults. The main questions that this study aims to answer are: * Do healthy young AA adults have a larger decrease in kidney blood flow during exercise compared to W adults? * Do healthy young AA adults have a larger decrease in kidney blood flow during other types of stress compared to W adults? During two visits in the research lab, participants will: * Perform a fitness test * Perform cycling exercise while lying down * Undergo a cold hand test * Perform a mental math test Completing this clinical trial will help researchers to understand more about why many AA adults have heart and kidney problems, so future research can study ways to reduce the number of AA adults who have these health issues.

Detailed description

African American (AA) adults have a greater prevalence of developing cardiovascular and renal disease (CVRD) than White (W) adults. Elevated sympathetic nervous system activity is associated with increased incidence of CVRD. Physical exertion, such as exercise, acutely increases sympathetic nervous system activity directed towards the kidneys, resulting in renal vasoconstriction and reduced renal blood flow (RBF). Limited research shows that healthy young AA adults exhibit exaggerated sympathetic responsiveness both at rest and during sympathetic activation, which may be a major contributor to the increased risk of CVRD in this population. However, the acute renal vasoconstrictor response to any sympathetic nervous system activation has not been investigated to date in AA adults. During sympathetic nervous system activation such as exercise, sympathetic outflow to the kidneys in AA adults might be exaggerated, contributing to greater renal vasoconstriction and a larger reduction in RBF. Over time, this exaggerated neurovascular response to sympathetic activation could have a negative cumulative effect on the kidneys, which could be a contributing factor to the greater incidence of CVRD in this population. Therefore, this study aims to examine the renal vasoconstrictor response to sympathetic stressors in healthy AA adults prior to development of CVRD, which will be achieved via two Specific Aims. In Specific Aim 1, the investigators will test the hypothesis that the renal vasoconstrictor response to acute dynamic exercise is exaggerated in healthy young AA compared to W adults. Specifically, the investigators will measure RBF and blood pressure at rest and during cycling exercise to calculate renal vascular resistance responses to exercise, enabling us to test the hypothesis that healthy young AA adults exhibit an exaggerated renal vasoconstrictor response to acute cycling exercise compared to healthy young W adults. In Specific Aim 2, the investigators will test the hypothesis that the renal vasoconstrictor response to non-exercise sympathetic stressors is exaggerated in healthy young AA compared to W adults. Specifically, the investigators will measure RBF and blood pressure at rest and during a cold pressor and mental stress tests to calculate renal vascular resistance responses to these non-exercise sympathetic stressors, enabling us to test the hypothesis that healthy young AA adults exhibit exaggerated renal vasoconstrictor responses to non-exercise sympathetic stressors compared to healthy young W adults. Using the highly innovative approach of Doppler ultrasound to measure RBF during exercise and non-exercise sympathetic stressors non-invasively and with high temporal resolution will enable us to assess the renal vasoconstrictor response to sympathetic stressors in healthy AA adults prior to development of CVRD, so the underlying integrative physiological responses to sympathetic activation in AA adults can be understood. Findings from this study in this understudied yet clinically significant area will contribute to the ultimate goal of creating and implementing treatment strategies to reduce the risk of developing CVRD in AA adults.

Conditions

• Healthy

Interventions

Type	Name	Description
OTHER	Acute exercise	Participants will lie in a semi-supine position with their feet attached to the pedals of a custom-arranged cycle ergometer. Participants' 40% heart rate reserve will be calculated, giving the target value to achieve during exercise based on appropriate resistance applied on the cycle ergometer, corresponding to a moderate exercise intensity. After a 5-minute resting baseline, participants will perform dynamic cycling exercise at steady state for up to 20 minutes. They will then stop exercising, and there will be a 5-minute recovery period. Beat-to-beat renal blood flow velocity (Doppler ultrasound), mean arterial blood pressure (finger photoplethysmographic cuff), and heart rate (electrocardiogram) will be recorded throughout. A rating of perceived exertion will be taken from participants during the last 30 seconds of steady-state cycling exercise.
OTHER	Cold pressor test	Participants will lie in a semi-supine position, and after a 3-minute resting baseline, participants will have their hand immersed in ice water for 2 minutes. This cold pressor test represents the non-exercise, physical sympathetic stressor. Participants' hand will then be removed from the ice water, followed by a 3-minute recovery period. Beat-to-beat renal blood flow velocity (Doppler ultrasound), mean arterial blood pressure (finger photoplethysmographic cuff), and heart rate (electrocardiogram) will be recorded throughout. Ratings of hand pain and cold perception will be taken from participants during the last 30 seconds of the cold pressor test.
OTHER	Mental stress test	Participants will lie in a semi-supine position, and after a 3-minute resting baseline, participants will perform a mental arithmetic task for 5 minutes. This mental stress test represents the non-exercise, psychological sympathetic stressor. Participants will be instructed to subtract a given number from a randomly selected three-digit number and verbally state their answer and continue to do so for the duration of the test. Participants will be instructed to state their answers as quickly and accurately as possible. Participants will then stop the arithmetic task, and a 3-minute recovery period will follow. Beat-to-beat renal blood flow velocity (Doppler ultrasound), mean arterial blood pressure (finger photoplethysmographic cuff), and heart rate (electrocardiogram) will be recorded throughout. A rating of perceived stress will be taken from participants during the last 30 seconds of the mental stress test.

Timeline

• Start date: 2024-09-30
• Primary completion: 2026-04-01
• Completion: 2026-04-01
• First posted: 2019-06-11
• Last updated: 2025-12-24

Locations

1 site across 1 country: United States