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 a nd phospholipids in skeletal muscle from rats subjected to 4 h of isch emia followed by 1-h reperfusion were analyzed by high-performance liq uid chromatography. In addition, ATP, phosphocreatine (PCr), P-i, and phosphomonoesters (PME) were analyzed by P-31-nuclear magnetic resonan ce at 202.4 MHz, and individual PME such as glucose-6-phosphate and TM P were quantified. PCr and ATP were exhausted after 4 h of ischemia an d recovered poorly upon reperfusion in the soleus and tibialis muscle of untreated rats. Postischemic reperfusion resulted in significant lo ss of cardiolipin. Treatment with 55 mM ascorbate resulted in total re storation of PCr during reperfusion, and ATP recovered to 42% of contr ol in the soleus. Recovery was improved in the tibialis as well, and t he 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 mu scle during postischemic reperfusion, probably due to its antioxidant function.