Actively Recruiting
Autonomic Control of the Circulation and the Venous Distension Reflex
Led by Milton S. Hershey Medical Center · Updated on 2026-06-02
18
Participants Needed
1
Research Sites
13 weeks
Total Duration
On this page
Sponsors
M
Milton S. Hershey Medical Center
Lead Sponsor
N
National Heart, Lung, and Blood Institute (NHLBI)
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are studying the venous distension reflex (VDR) in healthy adults aged 21 to 35 years. The study aims to understand how blocking the cyclooxygenase (COX) system with the drug ketorolac tromethamine affects muscle sympathetic nerve activity (MSNA) and vein size during limb venous distension. This research explores whether COX byproducts directly stimulate nerve responses or cause vein dilation that leads to nerve stimulation. Participants undergo a wrist-to-elbow occlusion procedure on one arm, followed by two infusions: first, ketorolac tromethamine to block the COX pathway, then a second infusion to induce venous distension. On a separate day, a control trial with saline infusions is performed. During the procedure, vein size is measured using a 3T MRI scanner while blood pressure and heart rate are recorded. Throughout the 3-4 hour study visit, continuous monitoring includes microneurography (MSNA), MRI vein imaging, heart rate, blood pressure, laser-Doppler flowmetry, strain gauge, and impedance measurements. Participants will be observed during the infusions and occlusion procedures to assess physiological responses. The study helps clarify the mechanisms involved in venous reflexes and circulatory control.
CONDITIONS
Brief Title
Autonomic Control of the Circulation and VDR
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Able to give informed consent
- Any race or ethnicity
- Fluent in written and spoken English
- Have a satisfactory medical history and physical exam
- Free of acute or chronic medical conditions
- Age between 21 and 35 years inclusive
- Weigh over 50 kg
You will not qualify if you...
- Under 21 or over 35 years of age
- Pregnant or nursing women
- Prisoners, institutionalized individuals, or unable to consent
- Chronic diseases such as hypertension, heart, lung, neuromuscular, kidney disease, diabetes, or cancer
- Taking medications affecting cardiovascular or nervous system
- Taken NSAIDs within 48 hours before any visit
- Never taken NSAIDs and unknown allergy status
- Supine blood pressure over 140/90 mmHg
- Known allergy to ibuprofen-like drugs, NSAIDs, or aspirin
- History of asthma or nasal polyps
- History of gastrointestinal bleeding or ulcers
- Ferromagnetic metal implants
- Claustrophobia
AI-Screening
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Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Two separate study visits, each lasting 3 to 4 hours
Participants will undergo the Wrist-to-Elbow occlusion procedure followed by two infusions into the occluded arm on two separate days: one with ketorolac tromethamine (a COX blockade) and one with saline as a control. During each 3 to 4 hour study visit, physiological measurements and imaging will be recorded continuously.
2 visits (in-person) on separate days
Trial Site Locations
Total: 1 location
1
Penn State Milton S. Hershey Medical Center
Hershey, Pennsylvania, United States, 17033
Actively Recruiting
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
CROSSOVER
Primary Purpose
BASIC_SCIENCE
Number of Arms
2
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