Sympathetic Neurovascular Transduction: Role of Adrenergic Receptors and Sex Differences
University of Alberta
30 participants
Oct 31, 2023
INTERVENTIONAL
Conditions
Summary
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.
Eligibility
Inclusion Criteria4
- 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 Criteria10
- 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 pregnant, confirmed by a pregnancy test.
- Females who have are less than 1 year postpartum or are breastfeeding.
- Females who are post-menopausal.
- Participants that are classified as obese (body mass index \> 30 kg ⋅ m2).
- Those with a known allergy to sulfites, or other components of the supplied solution of study drugs.
- 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.
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Interventions
Participants will receive three incremental doses via the brachial artery catheter to assess α1-adrenoreceptor mediated vasoconstriction.
Participants will receive four incremental doses via the brachial artery catheter to assess β-adrenoreceptor mediated vasodilation.
Participants will receive three incremental doses via the brachial artery catheter to assess nonspecific adrenoreceptor activation.
Propranolol will be continuously infused through the brachial artery catheter to induce β-adrenergic blockade locally in the forearm.
Phentolamine will be continuously infused through the brachial artery catheter to induce α-adrenergic blockade locally in the forearm.
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the α-adrenergic blockade.
Participants will receive one dose via the brachial artery catheter to evaluate the effectiveness of the β-adrenergic blockade.
Propranolol will be continuously co-infused with phentolamine to maintain the β-adrenergic blockade.
Locations(1)
View Full Details on ClinicalTrials.gov
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NCT05997732