PURINE METABOLIC PATHWAYS IN RAT HINDLIMB PERFUSION MODEL DURING ISCHEMIA AND REPERFUSION

The perfused rat hindlimb preparation was used with a blood cell-free perfusate to investigate alterations in the purine nucleotide metaboli sm, flow rate, perfusion pressure, and venous excretion in response to ischemia and ischemia followed by reperfusion in skeletal muscle. The development of a physical hindrance during postischemic reperfusion, indicated by an increase in reperfusion pressure and a decrease in flo w rate, coincided with a 90% decrease in phosphocreatine and a 50-70% reduction in total adenine nucleotide pool. The reflow impairment coul d not be explained by blood cell plugging of the capillaries. Washout of several metabolites was demonstrated during reperfusion. Hypoxanthi ne accumulated intracellularly during ischemia, and a substantial amou nt of uric acid was excreted into the venous effluent during reperfusi on. The experimental data were fitted into a computer simulation model of the purine pathways. The model indicated that AMP deaminase was th e predominant enzymatic pathway for the AMP degradation. It was demons trated that ATP preferably accumulated as inosine-5'-monophosphate dur ing ischemia and that xanthine oxidase was undetectable in skeletal mu scle tissue homogenates. However, vascular endothelial cell xanthine o xidase activity responsible for a free radical-induced reperfusion inj ury could not be excluded.