Laminar Shear Stress Pre‐Conditioning Restores VEGFR2 Activation Following an Oxidant Challenge in Endothelial Cells

Activation of vascular endothelial growth factor receptor 2 (VEGFR2) mediates critical downstream signaling pathways of endothelial function. Hydrogen peroxide (H 2 O 2 ) levels are elevated in hypertensives, and chronic exposure of endothelial cells (ECs) to H 2 O 2 may affect receptor activation. However, laminar shear stress (LSS) as a mimetic of exercise may attenuate detrimental effects of H 2 O 2 . This study examined VEGFR2 activation in response to H 2 O 2 mediated VEGF signaling, and LSS and H 2 O 2 mediated VEGF signaling. LSS (15 dyne/cm 2 , 6hrs) was applied as pre‐conditioning, followed by H 2 O 2 challenge (10uM, 30min). To alleviate the direct effects of H 2 O 2 on VEGF signaling, cells were washed and fresh media was added for 2hrs. VEGF (50ng/ml) was then used to stimulate the receptor. Western blot analysis was used for pVEGFR2(1175) and VEGFR2. H 2 O 2 challenge significantly attenuated VEGF mediated VEGFR2 activation in the absence of LSS. However, LSS pre‐conditioning restored VEGF mediated VEGFR2 activation following a H 2 O 2 challenge to LSS preconditioning VEGF mediated VEGFR2 activation levels. It appears that in vivo levels of H 2 O 2 are detrimental to VEGFR2 activation. However, the detrimental effects of H 2 O 2 are mitigated following LSS pre‐conditioning. Therefore, the ability of ECs to handle oxidative challenge may be enhanced following exercise induced improvement of the endothelium. NIH/NHLBI RO1 HL085497 & NIH/NIA KO1 AG019640