Purine nucleotides and phospholipids in ischemic and reperfused rat skeletal muscle: effect of ascorbate

The effect of intravenously administered ascorbate on the ischemic and reperfused rat skeletal muscle was investigated. Purine nucleotides and phospholipids in skeletal muscle from rats subjected to 4 h of ischemia followed by 1-h reperfusion were analyzed by high-performance liquid chromatography. In addition, ATP, phosphocreatine (PCr), Pi, and phosphomonoesters (PME) were analyzed by 31P-nuclear magnetic resonance at 202.4 MHz, and individual PME such as glucose-6-phosphate and IMP were quantified. PCr and ATP were exhausted after 4 h of ischemia and recovered poorly upon reperfusion in the soleus and tibialis muscle of untreated rats. Postischemic reperfusion resulted in significant loss of cardiolipin. Treatment with 55 mM ascorbate resulted in total restoration of PCr during reperfusion, and ATP recovered to 42% of control in the soleus. Recovery was improved in the tibialis as well, and the cardiolipin decrease was limited. A lower ascorbate concentration (5 mM) did not enhance postischemic recovery. Our findings show that a high dose of ascorbate improves the energetic state of rat skeletal muscle during postischemic reperfusion, probably due to its antioxidant function.