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

Summary

The goal of this preliminary study is to learn if healthy older 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 older AA adults have a larger decrease in kidney blood flow during exercise compared to W adults? * Do healthy older AA adults have a larger decrease in kidney blood flow during other types of stress compared to W adults? During one visit in the research lab, participants will: * Perform cycling exercise while lying down * Undergo a cold hand test * Perform a mental math test Completing this preliminary study 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.

Description

Eligibility

Age range

55–79 years

Sex

All

Healthy volunteers

Yes

Interventions

• 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.

Location