Acute impact of retrograde shear rate on brachial and superficial femoral artery flow-mediated dilation in humans.

Tim H A Schreuder,Daniel J Green,Maria T E Hopman,Dick H J Thijssen

doi:10.1002/phy2.193

Abstract

Retrograde shear rate (SR) in the brachial artery (BA) is associated with endothelial dysfunction; a precursor to atherosclerosis. The BA does not typically manifest clinical atherosclerosis, whereas the superficial femoral artery (SFA) is more prone to developing plaque. Examine whether the impact of incremental levels of retrograde SR differs between atherosclerosis‐prone (i.e., SFA) and ‐resistant vessels (i.e., BA) in healthy men. Thirteen healthy young men reported three times to the laboratory. We examined BA flow‐mediated dilation (FMD) before and after 30‐min exposure to cuff inflation around the forearm at 0, 30, and 60 mmHg, to manipulate retrograde SR. Subsequently, the 30‐min intervention was repeated in the SFA, using the same cuff pressure as in the forearm. Order of testing (vessel and intervention) was randomized among subjects. We found a dose‐dependent increase in retrograde SR with 30 and 60 mmHg cuff inflation, which was present in both the BA and SFA (all P < 0.05). BA and SFA FMD decreased after the 30‐min intervention (“time”: P = 0.012), and this was dependent on cuff pressure (“cuff × time”: P = 0.024). A significant decrease in FMD was observed after 60 mmHg only and this change was similarly present in both arteries (“time × artery”: P = 0.227). Moreover, the BA and SFA demonstrate a similar relationship between changes in retrograde SR and FMD (r = 0.498 and 0.475, respectively). Our study demonstrates that acute exposure to an increase in retrograde shear leads to comparable decreases in FMD in atherosclerotic‐prone and ‐resistant conduit arteries in humans.

Highlights

Shear stress, that is, the frictional force of blood on the arterial wall, represents an important stimulus for arteries to adapt (Niebauer and Cooke 1996; Thijssen et al 2009; Tinken et al 2009)
We found no difference in preintervention superficial femoral artery shear rate patterns, whereas the brachial artery showed a significantly higher baseline retrograde shear rate before the 30 mmHg intervention (Table 2)
The purpose of this study was to examine the acute impact of dose-dependent increases in retrograde shear on endothelial function in atherosclerotic-prone and -resistant arteries in humans

Summary

Introduction

That is, the frictional force of blood on the arterial wall, represents an important stimulus for arteries to adapt (Niebauer and Cooke 1996; Thijssen et al 2009; Tinken et al 2009). Previous animal studies demonstrated that antegrade shear stress is associated with positive, antiatherogenic effects on the endothelium (Chappell et al 1998; Hsiai et al 2003; Newcomer et al 2008; Tinken et al 2009, 2010; Wang et al 2013), whereas retrograde shear stress is associated with proatherogenic effects on the endothelium (Widlansky et al 2003; Thijssen et al 2009; Newcomer et al 2011). Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

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