Comparing 3 approaches for vasoconstriction
Official title: Sympathetic Neurovascular Transduction: Role of Adrenergic Receptors and Sex Differences
- Phase 4
- 3 groups
- One site, in Edmonton
- Recruiting
Interventions (8)
- Medication
Phenylephrine Hydrochloride
Participants will receive three incremental doses via the brachial artery catheter to assess α1-adrenoreceptor mediated vasoconstriction.
- Medication
Isoproterenol Hydrochloride
Participants will receive four incremental doses via the brachial artery catheter to assess β-adrenoreceptor mediated vasodilation.
- Medication
Norepinephrine Bitartrate
Participants will receive three incremental doses via the brachial artery catheter to assess nonspecific adrenoreceptor activation.
- Medication
Propranolol Hydrochloride
Propranolol will be continuously infused through the brachial artery catheter to induce β-adrenergic blockade locally in the forearm.
- Medication
Phentolamine Mesylate
Phentolamine will be continuously infused through the brachial artery catheter to induce α-adrenergic blockade locally in the forearm.
- Medication
Phenylephrine Hydrochloride
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the α-adrenergic blockade.
- Medication
Isoproterenol Hydrochloride
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the β-adrenergic blockade.
- Medication
Propranolol Hydrochloride
Propranolol will be continuously co-infused with phentolamine to maintain the β-adrenergic blockade.
Canadian Sites (1)
1 of 1 recruiting
- Recruiting
University of Alberta
Edmonton, Alberta
Eligibility Criteria
See who this study is looking for15 criteria
The trial’s own eligibility text, word for word from the registry. Only the trial site can say who takes part.
Inclusion
- +Between ages 18-40 years
- +No diagnosed medical history of cardiovascular, respiratory, nervous system, or metabolic disease.
- +Females must be pre-menopausal.
- +Prior to study visit: abstained from caffeine, alcohol, strenuous exercise, and medication not taken regularly for at least 12 hours.
Exclusion
- −Those with a known allergy to sulfites, or other components of the supplied solution of study drugs.
- −Current diagnosis of cardiovascular, respiratory, nervous system, or metabolic disease that may impact blood pressure regulation. This will be assessed on a case-by-case basis by the study physician.
- −Participants with bleeding or clotting disorders, or those currently taking blood thinners.
- −Participants currently taking beta-agonist inhalers i.e. Ventolin (at least not in the last 24 hours).
- −Females who are post-menopausal.
- −Participants that are classified as obese (body mass index \> 30 kg ⋅ m2).
- −Participants taking medications that are contraindicated with any of the study drugs, such as monoamine oxidase (MAO) inhibitors or tricyclic antidepressants.
- −Participants who have not adhered to the pre-testing guidelines related to diet, alcohol or exercise will not be excluded, but will be rescheduled for a different day. This is to reduce experimental variability.
- −Females who are pregnant, confirmed by a pregnancy test.
- −Females who have are less than 1 year postpartum or are breastfeeding.
- −Have a history of smoking regularly in the last 6 months (but nicotine substitutes (i.e. patch, gum) are not an exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more →).
In plain language
Assembled directly from this trial’s registry record. Every sentence traces to a field below — nothing here is generated or interpreted.
What this study is
This study is investigating how something functions in the body, rather than testing a treatment directly.
Phase 4Phase 4A study of a treatment that is already approved and in use.Read more → — a study of a treatment already approved for use, following it in everyday practice.
From the trial registry
Built from these fields:
- designModule.designInfo.primaryPurpose
- designModule.phases
Who receives what
There are 3 groups in this study.
Group A receives one or more of: Phenylephrine Hydrochloride, Isoproterenol Hydrochloride and Norepinephrine Bitartrate.
Registry label: A: Control Condition
Group B receives one or more of: Norepinephrine Bitartrate and Propranolol Hydrochloride.
Registry label: B: β-Adrenergic Blockade
Group C receives one or more of: Phentolamine Mesylate, Phenylephrine Hydrochloride, Isoproterenol Hydrochloride and Propranolol Hydrochloride.
Registry label: C: α+β-Adrenergic Blockade
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].label
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
How the study is run
Groups are assigned by the study team using set rules, rather than by chance.
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
From the trial registry
Built from these fields:
- designModule.designInfo.allocation
- designModule.designInfo.maskingInfo.masking
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
Who the study is looking for
The study lists an age range of 18 years to 40 years.
The study is open to people of any sex.
The study accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
These are the criteria the study lists. Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part.
From the trial registry
Built from these fields:
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How big and how long
The study aims to enrol about 30 people.
The study is currently expected to finish around December 2027.
The main measurement is taken over: 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
From the trial registry
Built from these fields:
- designModule.enrollmentInfo.count
- statusModule.completionDateStruct.date
- outcomesModule.primaryOutcomes[].timeFrame
What the study measures
Forearm blood flow — measured over 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
Forearm vascular resistance — measured over 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
Forearm vascular conductance — measured over 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
Arterial blood pressure — measured over 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
The study lists 3 further main measurements.
From the trial registry
Built from these fields:
- outcomesModule.primaryOutcomes[].measure
- outcomesModule.primaryOutcomes[].timeFrame
Source: NCT05997732 on ClinicalTrials.gov. The full registry text is further down this page — this summary never replaces it.
Not medical advice. What do these terms mean?
What is being tested — in plain terms
About Phenylephrine HydrochlorideDrug
Participants will receive three incremental doses via the brachial artery catheter to assess α1-adrenoreceptor mediated vasoconstriction.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Isoproterenol HydrochlorideDrug
Participants will receive four incremental doses via the brachial artery catheter to assess β-adrenoreceptor mediated vasodilation.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Norepinephrine BitartrateDrug
Participants will receive three incremental doses via the brachial artery catheter to assess nonspecific adrenoreceptor activation.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Propranolol HydrochlorideDrug
Propranolol will be continuously infused through the brachial artery catheter to induce β-adrenergic blockade locally in the forearm.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Phentolamine MesylateDrug
Phentolamine will be continuously infused through the brachial artery catheter to induce α-adrenergic blockade locally in the forearm.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Phenylephrine HydrochlorideDrug
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the α-adrenergic blockade.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Isoproterenol HydrochlorideDrug
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the β-adrenergic blockade.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About Propranolol HydrochlorideDrug
Propranolol will be continuously co-infused with phentolamine to maintain the β-adrenergic blockade.
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
Common questions
Answered from this trial’s registry record. Where the record doesn’t say, these answers say so rather than filling the gap.
Am I eligible for this trial?
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part. Concord cannot make that determination, and neither can any tool that has not examined you.
What the study lists: an age range of 18 years to 40 years.
The full inclusionInclusion criteriaThe things you must have or be for a study to consider you.Read more → and exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more → are published on this page, exactly as the study team wrote them.
The useful next step is to bring this trial to your doctor. Answering a few questions first gives them something concrete to review.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.eligibilityCriteria
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
- armsInterventionsModule.armGroups[].type
Would I know which treatment I am getting?
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
Groups are assigned by the study team using set rules, rather than by chance.
From the trial registry
- designModule.designInfo.maskingInfo.masking
- designModule.designInfo.allocation
Who can join?
The study lists an age range of 18 years to 40 years.
It is open to people of any sex.
It accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can confirm whether a particular person can take part.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How long would this take?
The study's main measurement is taken over: 10 minutes per condition + 2 minutes per agonist dose = 60 minutes.
The study as a whole is currently expected to finish around 2027-12-01.
How long any one person takes part can differ from the study length. The study team can tell you what the schedule looks like in practice.
From the trial registry
- outcomesModule.primaryOutcomes[].timeFrame
- statusModule.completionDateStruct.date
How many people are taking part?
The study aims to enrol about 30 people.
From the trial registry
- designModule.enrollmentInfo.count
Where is this happening?
This study lists one location: Edmonton, Alberta, Canada.
Sites can open and close during a study, so confirm with the team before travelling.
From the trial registry
- trial_locations
About This Trial
The main purpose of this interventional study is to examine differences in resting blood pressure control between healthy males and females. The main questions it aims to answer are: 1. Are there sex differences in the communication between the sympathetic nervous system (also known as the "fight or flight" response) and peripheral blood vessels (which influence systemic blood pressure)? 2. What is the role of specific vascular receptors that respond to sympathetic signals, and is it different between males and females? Participants will complete one study visit of approximately 3 hours where they will: * Have a blood sample taken to measure circulating sex hormone and sympathetic transmitters. * Receive very small doses of medications commonly used to adjust blood pressure through an artery in their arm. The effects of these medications will be short-acting and localized to the forearm. * Have their sympathetic nervous activity directly measured through two very small needles (similar to acupuncture needles) in the side of their leg. * Have their blood pressure and heart rate recorded, and forearm blood flow measured using ultrasound.
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See if this trial could fit youThis page is for informational purposes only and does not constitute medical advice. Clinical trial eligibility can only be determined by the trial site after proper screening. Trial information is sourced from ClinicalTrials.gov and may not reflect the most current status. Always consult your healthcare provider before making decisions about clinical trial participation.