Sex differences in how sympathetic nerves and adrenergic receptors change blood vessel tone
Sympathetic Neurovascular Transduction: Role of Adrenergic Receptors and Sex Differences
This study will try small, localized drug infusions and direct nerve recordings in healthy men and women to see if their blood vessels respond differently to sympathetic signals.
Quick facts
| Phase | Phase 4 |
|---|---|
| Study type | Interventional |
| Enrollment | 30 (estimated) |
| Ages | 18 Years to 40 Years |
| Sex | All |
| Sponsor | University of Alberta Academic / other |
| Locations | 1 site (Edmonton, Alberta) |
| Trial ID | NCT05997732 on ClinicalTrials.gov |
What this trial studies
This interventional, single-visit protocol enrolls healthy adults to compare neurovascular transduction between sexes by combining direct sympathetic nerve recordings with localized intra-arterial drug infusions. Participants provide a blood sample for sex hormones and sympathetic transmitters, undergo microneurography using very small needles to record sympathetic nerve activity, and receive short-acting, low-dose vasoactive drugs delivered to the forearm to probe α- and β-adrenergic receptor function. Vascular responses to norepinephrine, phenylephrine, isoproterenol, and receptor blockade agents (propranolol, phentolamine) are measured to determine how receptor activity differs between males and females. The visit lasts about three hours and the drug effects are localized and short-lived.
Who should consider this trial
Good fit: Healthy adults aged 18–40, including premenopausal females who are not pregnant, postpartum within one year, or breastfeeding, and who can abstain from caffeine, alcohol, strenuous exercise, and nonregular medications before the visit.
Not a fit: People with diagnosed cardiovascular, respiratory, neurologic, or metabolic disease, those with bleeding/clotting disorders or on blood thinners, obese individuals (BMI > 30), pregnant or recent postpartum/breastfeeding women, and others excluded by the protocol are unlikely to benefit or be eligible.
Why it matters
Potential benefit: If successful, the results could improve understanding of sex-specific blood pressure control and help guide more tailored approaches to treating or preventing blood pressure problems in men versus women.
How similar studies have performed: Prior human and animal studies have reported sex differences in sympathetic activity and greater β-adrenergic vasodilation in females, but combining direct microneurography with localized pharmacologic infusions is relatively novel.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * 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 Criteria: * 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). * Have a history of smoking regularly in the last 6 months (but nicotine substitutes (i.e. patch, gum) are not an exclusion criteria). * 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.
Where this trial is running
Edmonton, Alberta
- University of Alberta — Edmonton, Alberta, Canada (Recruiting)
Study contacts
- Principal investigator: Sean van Diepen, MD, MSc — University of Alberta
- Study coordinator: Emily Vanden Berg, MSc
- Email: ervanden@ualberta.ca
- Phone: (780)-492-5553
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.