Association between wall shear stress and flow-mediated vasodilation in healthy men

Wall shear stress contributes to the endothelial production of vasoactive mediators, like nitric oxide (NO). Brachial artery vasodilation that follows increased blood flow is regulated by NO release. Aim of the present study was to investigate whether resting wall shear stress of the brachial artery is related to flow-mediated vasodilation (FMD) induced by forearm ischemia. Wall shear stress was calculated according to the following formula: Wall shear stress=Blood viscosity x Blood velocity/Internal diameter. FMD was calculated as percentage change of brachial artery diameter following forearm ischemia. Twenty-seven healthy male subjects were investigated. Peak wall shear stress and FMD were 37.3+/-12.8 dynes/cm(2) and 110.7+/-5.6%, respectively (mean+/-S.D.). In simple regression analyses, age was inversely associated with wall shear stress (r=48, P<0.01) and, marginally, with FMD (r=0.33, P=0.08). Wall shear stress and FMD were directly related (r=0.60, P<0.001). In multiple regression analysis, including wall shear stress, age, blood pressure, lipids, glucose and Body Mass Index as independent variables, wall shear stress was the only variable independently associated with FMD (standardized beta coefficient=0.690, P