NCT02947750 · Emory University
Neurovascular Transduction During Exercise in Chronic Kidney Disease
(NeurovEx)
What this study is about
The purpose of this study is to find out why patients with chronic kidney disease (CKD) have poor exercise capacity and to explore what causes an increase in blood pressure during exercise (i.e. increased adrenaline levels, or decreased ability of blood vessels to dilate).
View original scientific description
The purpose of this study is to find out why patients with chronic kidney disease (CKD) have poor exercise capacity and to explore what causes an increase in blood pressure during exercise (i.e. increased adrenaline levels, or decreased ability of blood vessels to dilate). This study will also test whether or not regular exercise on a bicycle and/or treatment with 6R-BH4 (Kuvan) pills, or histidine and beta-alanine supplementation improves these measures during exercise.
Interventions
DRUG
6R-BH4
Participants will receive 200 mg of 6R-BH4 twice daily for 12 weeks. Study pills are dissolved in water or apple juice, and taken with food.
OTHER
6R-BH4 placebo
Participants will receive a placebo that is identical to 200 mg of 6R-BH4. The placebo will be taken twice daily for 12 weeks. Study pills are dissolved in water or apple juice, and taken with food.
DIETARY_SUPPLEMENT
Folic acid
Participants will take 1 mg of folic acid daily for 12 weeks. Folic acid is given because it enhances the binding affinity of BH4 to nitric oxide synthase (NOS), and also enhances the regeneration of BH4 from inactive BH2
OTHER
Exercise training
Participants will exercise 3 times a week on a stationary ergometer. Exercise intensity will begin at low levels (50% of maximal heart rate reserve) calculated utilizing the Karvonen method. Briefly, target exercise heart rate (HR) is calculated by subtracting the persons age from 220. Resting heart rate is then subtracted from this number. The answer is then multiplied by the target percent (50% for example) and the product is added back to resting heart rate to provide the target exercise session heart rate. Intensity will be increased by 5% every week (as tolerated by the participant) to a maximum of 80% of maximal heart rate. Exercise time will progress from an initial 20 minutes per session to a maximum of 45 minutes by increasing 5 minutes each week.
OTHER
Stretching
Participants randomized to 'No Exercise Training' group will instead of aerobic exercise, undergo progressive whole body stretching and toning exercises designed for individuals 65 and older. This type of low intensity activity is designed not to increase heart rate and will serve as the Control group to the Exercise Training group. The Control group will come in for stretching sessions 3 times per week for 20-45 minutes.
DIETARY_SUPPLEMENT
Histidine and beta-alanine supplementation
Histidine and beta-alanine are two over-the-counter supplements commonly used to enhance sports performance in athletes. Participants randomized to this study arm will receive combined histidine (4g/day) and beta-alanine (3.2g/day) supplementation.
OTHER
Histidine and beta-alanine placebo
Participants randomized to this study arm will receive a placebo to match combined histidine (4g/day) and beta-alanine (3.2g/day) supplementation.
Primary outcome measures
Change in functional sympatholysis
Time frame: Baseline, Week 12
Muscle oxygenation during exercise and sympathoexcitation will be measured.
Change in vascular alpha 1 adrenergic responsiveness
Time frame: Baseline, Week 12
Changes in vascular diameter in response to phenylephrine will be measured.
Change in exaggerated pressor responses during exercise
Time frame: Baseline, Week 12
Blood pressure and sympathetic responses during exercise will be measured.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- for Chronic Kidney Disease Patients:
- Stage III or IV Chronic Kidney Disease, defined as reduction in estimated glomerular filtration rate (eGFR) to 15-59 cc/minute as calculated by the modified Modification of Diet in Renal Disease (MDRD) Study equation or the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation
- Stable renal function, with no greater than a 30% reduction in eGFR over the prior 3 months
- Does not exercise regularly (defined as exercising less than 20 minutes twice per week)
- Willing and able to cooperate with the study protocol Inclusion Criteria for Control Study Participants:
- Does not exercise regularly (defined as exercising less than 20 minutes twice per week)
- Willing and able to cooperate with the study protocol
Exclusion criteria
- severe CKD (eGFR\<15 cc/minute)
- ongoing drug or alcohol abuse
- diabetic neuropathy
- any serious systemic disease that might influence survival
- severe anemia with hgb level \<9 g/d
Where
- Atlanta, Georgia
- Decatur, Georgia
Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 18, 2026 · Source of record for eligibility and locations