Study of Sex Differences in Blood Vessel Responses and Adrenergic Receptor Effects on Blood Pressure in Healthy Adults Aged 18 to 40

What this Trial Is About

Researchers are investigating how resting blood pressure control differs between healthy males and females. The study focuses on the communication between the sympathetic nervous system, which controls the fight or flight response, and blood vessels that affect systemic blood pressure. It also examines how specific blood vessel receptors, called alpha and beta-adrenergic receptors, respond to sympathetic signals and whether their behavior differs by sex. Understanding these differences may help explain why blood pressure regulation varies between males and females. Participants will attend one approximately 3-hour study visit where they receive small doses of medications through a catheter in the arm to test blood vessel responses. These medications include blockers to alpha- and beta-adrenergic receptors, given alone or together, as well as agents that stimulate these receptors. During the visit, saline infusions control for volume effects. The study measures forearm blood flow and vascular resistance under different conditions with receptor blockades. During the visit, participants have blood samples taken to measure sex hormones and sympathetic neurotransmitters. Their muscle sympathetic nerve activity is recorded using fine needles in the leg. Blood pressure, heart rate, and forearm blood flow are monitored using ultrasound. The main outcomes measured include forearm blood flow, vascular resistance, vascular conductance, arterial blood pressure, muscle sympathetic nerve activity, and circulating hormone levels. The total study participation is a single visit, and safety is closely monitored throughout.

Sympathetic Neurovascular Transduction: Role of Adrenergic Receptors and Sex Differences