Urate metabolism in a mongrel dog.

(1) We have performed short-term turnover studies in a trained mongrel dog, and found remarkably linear turnover curves for both urate and its principle metabolic product, allantoin. (2) Infusions of Pyrazinamide, Probenecid, and Sodium Salicylate had no apparent effect on urate metabolism. (3) The "uricolytic index" for endogenous urate is consistenely lower than that of infused, isotopic urate. This finding suggests renal synthesis and direct excretion of unlabelled urate. (4) The renal clearance of labelled urate is higher than that of endogenous urate despite apparent renal synthesis. This finding suggests that urate may exist in more than one molecular form.