title: Alpha-adrenergic control of blood flow during exercise: effect of sex and menstrual phase.
abstract: Sex differences exist in autonomic control of the cardiovascular system. This study was designed to directly test sex or female menstrual phase-related differences in α-adrenergic control of blood flow during exercise. We hypothesized that women would exhibit reduced α-adrenergic vasoconstriction compared with men during exercise; in addition, women would constrict less during the early luteal than the early follicular phase of the female menses. Young men (n = 10) were studied once and women (n = 9) studied twice, once during the early follicular phase and once during the early luteal phase of female menses. We measured forearm blood flow (FBF; Doppler ultrasound of the brachial artery) during rest and steady-state dynamic exercise (15 and 30% of maximal voluntary contraction, 20 contractions/min). A brachial artery catheter was inserted for the local administration of α-adrenergic agonists [phenylephrine (PE; α(1)) or clonidine (CL; α(2))]. Blood flow responses to exercise [forearm vascular conductance (FVC)] were similar between all groups. At rest, infusion of PE or CL decreased FVC in all groups (40-60% reduction). Vasoconstriction to PE was abolished in all groups at 15 and 30% exercise intensity. Vasoconstriction to CL was reduced at 15% and abolished at 30% intensity in all groups; women had less CL-induced constriction during the early luteal than early follicular phase (P < 0.017, 15% intensity). These results indicate that vasodilator responses to forearm exercise are comparable between men and women and are achieved through similar paths of α-adrenergic vascular control at moderate intensities; this control may differ at low intensities specific to the female menstrual phase.
authors: Department of Kinesiology, School of Education, University of Wisconsin, Madison, WI 53706, USA.
authors: Jacqueline K
authors: JK
authors: Limberg
authors: Marlowe W
authors: MW
authors: Eldridge
authors: Lester T
authors: LT
authors: Proctor
authors: Joshua J
authors: JJ
authors: Sebranek
authors: William G
authors: WG
authors: Schrage
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage; D000328:Adult; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000294:innervation*; D015444:Exercise; D005260:Female; D005498:Follicular Phase; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D007261:Infusions, Intra-Arterial; D008183:Luteal Phase; D008297:Male; D008597:Menstrual Cycle; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*; D012039:Regional Blood Flow; D012737:Sex Factors; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism*; D014463:Ultrasonography; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000008:administration & dosage; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D000316:Adrenergic alpha-Agonists; D011942:Receptors, Adrenergic, alpha; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents