IN-VIVO P-31 NUCLEAR-MAGNETIC-RESONANCE EVIDENCE OF THE SALVAGE EFFECT OF ASCORBATE ON THE POSTISCHEMIC REPERFUSED RAT SKELETAL-MUSCLE

The effect of 32 mM ascorbate on the time courses of phosphocreatine ( PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP) and intra cellular pH in rat skeletal muscle during ischemia and reperfusion was investigated in vivo using P-31 nuclear magnetic resonance (NMR) spec troscopy. Ascorbate was administered intravenously prior to induction of ischemia and at the time of reperfusion. The changes in PCr/(PCr+Pi ), ATP and pH were similar in the non-treated and in the treated group s during ischemia. PCr(PCr+Pi) fell to <10% and ATP to approximately 3 0% of the preischemic values after 4 hours of arrested circulation, an d pH decreased considerably. Postischemic reperfusion was followed con tinuously for 150 minutes. At the time of reflow, treatment with ascor bate had an immediate, positive effect on the recovery of high energy phosphates and pH. The level of PCr/(PCr+Pi) was 86% higher p < 0.001) and the ATP level was 40% higher p < 0.001) in the treated group than in the control group by the end of the reperfusion period. The result s provide in vivo evidence for a salvaging effect of ascorbate on isch emia-reperfusion injury in skeletal muscle, probably owing to its anti oxidant function and other ancillary effects, mainly its provision of additional buffer capacity.