title: The impact of a cold pressor test on brachial artery handgrip exercise-induced flow-mediated dilation.
abstract: It is unknown how endothelial-dependent flow-mediated dilation (FMD) stimulated by a sustained, exercise-induced increase in shear stress (EX-FMD) is affected by a simultaneous sympathoexcitatory painful stimulus. The purpose of this study was to examine the impact of a cold pressor test (CPT) on brachial artery EX-FMD elicited by a handgrip exercise-induced increase in shear stress. Participants were healthy males (age 21±2 years) (n=28; 16 Experimental group, 12 Control). Brachial artery diameter and blood velocity were measured using echo and Doppler ultrasound, respectively. Shear stress was estimated by shear rate (shear rate = blood velocity / diameter) and targeted to reach 75 s(-1) in each of two EX-FMD trials in all subjects. In the Experimental group, the second EX-FMD trial was accompanied by simultaneous foot immersion in ice water (simultaneous CPT). The shear rate stimulus did not differ between groups (p=0.823) or trials (p=0.726) (group × trial interaction: p=0.646) (average exercise shear rate (mean ± SD): 67.6±6.2 s(-1)). The CPT (experienced during EX-FMD trial 2 in the Experimental group) increased mean arterial pressure (p<0.001) and heart rate (p=0.002) relative to the Control group. %EX-FMD was not different between groups (p=0.508) or trials (p=0.592) (group × trial interaction: p=0.879) (EX-FMD: Experimental group trial 1: 5.4±3.4%, trial 2: 5.6±2.6%; Control group trial 1: 6.0±3.7%, trial 2: 6.4±2.2%). In conclusion, the CPT did not impact concurrent EX-FMD, and this indicates that an acute painful stimulus does not interfere with conduit artery FMD responses during exercise in young healthy men.
authors.affiliation: School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada.
authors.forename: Troy J R
authors.initials: TJ
authors.lastname: Stuckless
authors.affiliation: School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada pykek@queensu.ca.
authors.forename: Kyra E
authors.initials: KE
authors.lastname: Pyke
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001916:Brachial Artery / Q000503:physiopathology*; D003080:Cold Temperature; D004730:Endothelium, Vascular / Q000502:physiology; D015444:Exercise; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology*; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology; D013314:Stress, Mechanical; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult
keywords: Blood vessels; FMD; brachial artery; endothelial function; shear stress; sympathetic activation; vascular endothelium; vasodilation