In vivo 31P 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 intracellular pH in rat skeletal muscle during ischemia and reperfusion was investigated in vivo using 31P nuclear magnetic resonance (NMR) spectroscopy. 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 groups during ischemia. PCr/(PCr+Pi) fell to < 10% and ATP to approximately 30% of the preischemic values after 4 hours of arrested circulation, and pH decreased considerably. Postischemic reperfusion was followed continuously for 150 minutes. At the time of reflow, treatment with ascorbate 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 results provide in vivo evidence for a salvaging effect of ascorbate on ischemia-reperfusion injury in skeletal muscle, probably owing to its antioxidant function and other ancillary effects, mainly its provision of additional buffer capacity.