Endothelial function and shear stress in hypobaric hypoxia: time course and impact of plasma volume expansion in men
Joshua C. Tremblay, Philip N. Ainslie, Rachel Turner, Hannes Gatterer, Maja Schlittler, Simon Woyke, Ivo B. Regli, Giacomo Strapazzon, Simon Rauch, Christoph Siebenmann
Abstract
Using a normoxic crossover study design, we examined the impact of hypobaric hypoxia (4 days; altitude equivalent, 3,500 m) and hemoconcentration on blood viscosity, shear stress, and endothelial function. Blood viscosity increased during the hypoxic exposure and was accompanied by elevated resting and exercising arterial shear stress. Flow-mediated dilation stimulated by reactive hyperemia and handgrip exercise was preserved throughout the hypoxic exposure. Plasma volume expansion reversed the hypoxia-associated hemoconcentration and selectively increased handgrip exercise flow-mediated dilation.