[The postnatal development of porcine purine catabolism and the effect of the environmental temperature on turnover].

Experiments in piglets indicate that the catabolic metabolism of purines is only developed during the first 4 weeks of life. During this time the catalytic activity of uricase in liver homogenates is increased about 5.5 fold (p < 0.01). The counts of uricase-carrying peroxisomes and cores are increased to a similar degree (p < 0.01). In the same time the catalytic activity of cytosolic xanthine oxidase is elevated about 4.6 fold (p < 0.01), mainly in the second and third week. In blood plasma uric acid is decreased from 19 to 12 molar % during weeks 1 to 4, hypoxanthine, xanthine and allantoin remain relatively constant. In urine xanthine and uric acid are decreased, hypoxanthine and allantoin are increased. At the age of 2-3 days a decrease of ambient temperature from 32 to 20 degrees C caused an increase of the plasma pool (p < 0.01) and turnover (p < 0.05) of uric acid. Pool size and turnover of hypoxanthine are only slightly elevated. The results are discussed in view of the slow development of hepatic enzymes, the increase of uric acid pool at lowered ambient temperature and causal events leading to urate nephropathia.