The acute effects of furosemide, ethacrynic acid and chlorothiazide on the renal tubular handling of uric acid in the chicken.

Birds resemble man in that both lack uricase and therefore uric acid (urate) is the end product of purine metabolism in both animals. Although urate is largely excreted by the kidneys in both species, it has generally been accepted that the renal handling of urate in the chicken differs from that in man in that drugs which are known to be uricosuric in man do not produce a uricosuric response in birds. This suggests that tubular reabsorption of urate is either minimal or lacking in birds. The present study used the in vivo Sperber chicken technique to investigate the acute effects of diuretics which are known to alter urate clearance in man. Our results show that both ethacrynic acid and furosemide can selectively increase the apparent tubular excretion of [14C]urate, suggesting that the chicken kidney is capable of reabsorbing urate. Chlorothiazide is known to decrease urate clearance in both man and the chicken and was found in this study also to decrease the renal tubular excretion of [14C]urate formed within the chicken kidney during infusion of [14C]hypoxanthine or [14C]guanine.