Cardiac adaptive responses after hypoxia in an experimental model

The role of vascular endothelial growth factor (VEGF) and erythropoietin (EPO) in mediating hypoxic preconditioning under the acute intermittent hypoxic condition (AIH) was investigated in this study. Male Wistar rats were randomly assigned and kept in normoxic conditions, (Nx) or in AIH conditions and subjected to brief cycles hypoxia/reoxygenation. Hearts were isolated, perfused, and subjected to in vitro global ischemia followed by reperfusion. During and at the end of reperfusion, left ventricular developed pressure (LVDP); LV end diastolic pressure (LVEDP); rate pressure product (RPP); peak left ventricular pressure rise (ΔP/Δt max ) and heart rate (HR) were measured. Hearts subjected to AIH displayed a significant higher LVDP (P <.001), RPP (P <.001), and ΔP/Δt max (P <.001). Expression of VEGF and EPO were significantly increased at 3, 8, and 24 hours after AIH. Hypoxic training could provide a new approach to enhance endogenous cardioprotective mechanisms.