title: Impaired brachial artery flow-mediated vasodilation in response to handgrip exercise-induced increases in shear stress in young smokers.
abstract: Smoking is an established risk factor for cardiovascular disease. It has also been shown to result in endothelial dysfunction as assessed by flow-mediated dilation (FMD) in response to reactive hyperemia (RH)-induced increases in shear stress. Handgrip exercise (HGEX) is an emerging alternative method to increase shear stress for FMD assessment (HGEX-FMD) and the purpose of this study was to identify the impact of smoking on HGEX-FMD in young healthy subjects. Brachial artery RH-FMD and HGEX-FMD (10-minute bout of HGEX) was assessed in eight smokers (S) and 14 non-smokers (NS) (age 21 ± 2 years). Brachial artery diameter and mean blood velocity were assessed with echo and Doppler ultrasound, respectively. Shear stress was estimated by shear rate (SR = brachial artery blood velocity/diameter). The SR stimulus did not differ between groups for either test (RH-FMD (SR area under the curve until peak diameter measurement), p = 0.897; HGEX-FMD (average SR over 10-minute exercise bout), p = 0.599). The RH-FMD magnitude was not significantly different between groups (S: 7.7 ± 2.2% vs NS: 7.9 ± 2.4%, p = 0.838); however, the HGEX-FMD magnitude was significantly impaired in smokers (S: 6.1 ± 3.4% vs NS: 9.6 ± 3.6%, p = 0.037). In conclusion, HGEX-FMD assessment detected vascular dysfunction in young healthy smokers while RH-FMD did not. This suggests that HGEX-FMD may be useful in the early detection of smoking-induced impairments in endothelial function. Further research is required to explore this phenomenon in other populations and to isolate underlying mechanisms.
authors.affiliation: School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada.
authors.forename: Briar B
authors.initials: BB
authors.lastname: Findlay
authors.forename: Parnika
authors.initials: P
authors.lastname: Gupta
authors.forename: Ingrid C
authors.initials: IC
authors.lastname: Szijgyarto
authors.forename: Kyra E
authors.initials: KE
authors.lastname: Pyke
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015444:Exercise; D006225:Hand / Q000098:blood supply; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology*; D012907:Smoking / Q000009:adverse effects*; D013314:Stress, Mechanical; D011795:Surveys and Questionnaires; D014463:Ultrasonography; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult