CONCENTRATION AND TRANSPORT OF TRUE URATE IN THE PLASMA OF THE AZOTEMIC CHICKEN

Publisher Website
Google Scholar
Abstract
Earlier reports of greatly elevated blood urate levels in the azotemic bird were confirmed for the chicken following bilateral ureteral ligation. The avg. plasma urate was 304 mg. %, of which 93.5% was true urate when studied by the specific uricase method. The plasma uric acid-like chromogen is also increased in the azotemic chicken, indicating its endogenous origin. Other data show that, as in the dog and in man, the physiologic behavior of chromogen in the chicken closely parallels that of true urate. A consideration of data obtained from the study of plasma and plasma ultrafiltrates by various methods in both the normal and azotemic chicken has suggested that urate may be transported as a 3-phase system. A small fraction, not over 25 mg. %, appears to be in true soln. while a somewhat larger fraction, averaging 55 mg. %, is transported as protein-bound urate. The largest amt., averaging 224 mg. %, is carried as ultrafiltrable polymeric or ultrafiltrable colloidal urate. Physicochemical methods at present do not permit the demonstration of such a 3-phase system when the plasma urate concn. is below the theoretic maximal solubility of urate in plasma water, a poorly defined value. A review of earlier data on the renal mechanism for urate excretion in the chicken indicates that the renal glomerulus is probably freely permeable to urate in true soln. and to ultrafiltrable polymeric urate in this sp., but that protein-bound urate may not be ultrafiltrable through the glomerulus of the chicken.