Stimulation of de novo biosynthesis of purine and pyrimidine nucleotides in the liver of rats following burn injury

Third-degree burn injury covering 25% of the body surface was imposed on rats. The de novo biosynthesis of purine and pyrimidine nucleotides in the liver of these rats was measured by the incorporation of labeled glycine and bicarbonate into the respective bases. They were increased one day after injury (day 2) and returned to the control values three days after injury (day 4). As expected, the metabolic flow through 5-phosphoribosyl 1-pyrophosphate ( PPRib P), estimated using [ 14C]ribose as a tracer, varied in a similar manner. The activities of glutamine phosphoribosylpyrophosphate amidotransferase and carbamoyl-phosphate synthetase II on day 2 did not change significantly. The nucleotide concentrations, effectors of the enzymes, also did not change significantly. The concentrations of PPRib P on days 2 and 4 were 85% higher ( P < .02) and similar to that of controls, respectively, and the elevated concentration was a major factor responsible for the increased nucleotide biosynthesis. Increased synthesis caused the elevation of PPRib P concentrations. There were, however, no significant changes in the factors so far known to regulate PPRib P synthesis.