HYPOXIC PRECONDITIONING PRESERVES ANTIOXIDANT RESERVE IN THE WORKING RAT-HEART

Objective: The aim was to examine whether intracellular antioxidants p lay a role in myocardial preservation following hypoxic preconditionin g. Methods: Isolated working rat hearts were subjected to 30 min ischa emia and 30 min reperfusion. Control hearts were compared to hearts pr econditioned with 10 min hypoxia. Left ventricular function and lactat e dehydrogenase (LDH) release were measured in each group. Ascorbate d ependent (ADAR) and thiol dependent (TDAR) components of the endogenou s myocardial antioxidant reserve were assessed using electron spin res onance spectroscopy. Results: Hypoxic preconditioning had no effect on left ventricular function after 10 min reoxygenation. During reperfus ion, the hypoxically preconditioned hearts had a significantly increas ed survival rate, aortic flow, developed pressure, and dP/dt(max), and a reduced lactate dehydrogenase release, compared to non-precondition ed controls (P<0.05). Preconditioned hearts also had significantly hig her preservation of baseline ADAR (79%) and TDAR (96%) compared with c ontrol hearts, (70%) and (77%), respectively (P<0.05). Conclusions: Hy poxic preconditioning enhances functional recovery and reduces cell ne crosis following global ischaemia in the working rat heart. This pheno menon may, in part, be mediated through enhanced ascorbate and thiol c omponents of the antioxidant reserve.