Background: Autophagy plays a critical role in cellular homeostasis by recycling damaged proteins and organelles. A contribution to the regulation of redox hemostasis has previously been described in vascular endothelial cells. Pathological stress such as elevated ROS can attenuate endothelial function and shear-induced NO formation, which under physiological conditions suppresses mitochondrial ROS production. We have previously shown that onset of disease (coronary artery disease; CAD) changes the endothelial cell response to flow in isolated human microvessels from production of NO to H2O2. We hypothesize that autophagic flux (AF) is necessary for shear-induced release of NO in isolated human microvessels (MV) and loss of autophagy results in excess oxidative stress and greater susceptibility to oxidant-induced injury. Methods: Human MVs (~200µm; MV) obtained from otherwise discarded surgical tissue (adipose and heart) were used for pressure myograph studies. Collection of human tissue samples was approved by institutional review board. Flow mediated dilation (FMD) and its mechanism was evaluated via video microscopy. Statistical significance (p-value of < 0.05) was determined via 2 way RM ANOVA tukey post hoc test (FMD) or t-test (lysotracker). Results: In cultured endothelial cells shear and Trichostatin A (TSA; 100nM) increased AF significantly and was blockage in the presence of 3-Methyladenine (3-MA; 5 mM) an inhibitor of autophagosome elongation. Using histochemistry and western blots we determined a significant decrease of the autophagy marker LC3B in tissue from subjects with CAD (Fig. 1) Incubation of MVs from non-CAD subjects with an inhibitor of lysosome formation, Bafilomycin A (BFA; 10 nM) decreased NO mediated dilation to compare to vehicle treated vessels (Fig. 2a). Interestingly in MVs from subjects with CAD TSA restored the mechanism of FMD to NO form the normally observed pathological H2O2 Fig. 2b). Conclusions: Our data suggest, that AF is a critical regulator of endothelial function. Under disease conditions (CAD) AF is reduced and likely contribute to the decrease NO mediated dilation with compensatory increase in H2O2. Pharmacological activation of AF is sufficient to restore a physiological (NO) dilation to flow in subjects with CAD.