Evidence that flow mediated dilation dynamics differ in smokers versus non‐smokers: a pilot study (677.6)

Abstract

Endothelial function is impaired in smokers as measured via handgrip exercise (HGEX) induced flow mediated dilation (FMD). The goal of this pilot study was to determine whether the dilation and reconstriction dynamics of FMD were impaired in young male smokers. 8 smokers and 14 non smokers (age 21 ± 2) performed 10 minutes of rhythmic HGEX bracketed by 4 minutes of arterial compression to ensure rapid shear stress onset and return to baseline. Brachial artery diameter and blood velocity assessed via echo and Doppler ultrasound. Shear stress estimated as shear rate (SR = brachial artery blood velocity/diameter). Dynamic parameters: time to onset of dilation and reconstriction (TD1); rate of dilation and reconstriction(Tau1). Alpha set at P<0.1, data ± SD. SR stimulus did not differ between groups(p=0.60). TD1 of dilation was longer in smokers (29.7 ± 17.0 s) vs. non smokers (17.5 ± 11.9 s)(p=0.06), and Tau1 was faster among smokers (27.5 ± 9.5 s vs. 48.6 ± 32.4 s, p = 0.09). Constriction dynamics were not different between groups (p>0.1). Among smokers, dilation tau1 was faster than reconstriction tau1(27.5 ± 9.5 s vs. 72.3 ± 56.4 s, p=0.06), whereas there were no differences between onset and constriction dynamics among non‐smokers (p=0.43). These results suggest that smoking impacts the dynamics of the vascular response to shear stress with a preferential impact on dilation vs. reconstriction. Grant Funding Source: Supported by NSERC and CFI