ON THE EXCRETION OF URIC ACID AND URATES BY THE BIRD

¹ From the Departments of Biochemistry and Pharmacology, Dalhousie University, Halifax, Nova Scotia

A study has been made of the ureteral excretion of uric acid by the cockerel. Under luminal anesthesia the urine is a viscous, cloudy fluid containing solid matter which consists of uric acid, or urate, or both. The normal average flow is 6.6 cc. per hour and the variation 2 to 15 cc. The variation in pH is 5.0 to 6.8 with a mean value of 5.5. The concentration of urate is usually at a level of supersaturation, 0.2 to 0.7 per cent, and a portion has been demonstrated to be colloidal by ultrafiltration. Under urethane anesthesia the urine is clear, less acid and less concentrated.

Birds whose ureters have been ligated die in about twenty-four hours and exhibit at post-mortem extensive deposits of uric acid or urate in the pleural, peritoneal and pericardial cavities and occasionally in the joints. The level of uric acid in the blood has never exceeded 0.091 per cent.

Colloidal preparations of monolithium urate, injected intravenously, are recovered in the urine to the extent of between 100 and 250 per cent, monosodium urate and hexamethylenetetramine urate between 40 and 100 per cent, piperidine urate little if at all. The extent of recovery is intimately related to the urinary volume.

Of substances which might increase the solubility of uric acid in the kidney mechanism lithium carbonate is most effective inducing marked diuresis and increasing the output of uric acid many fold. A similar action has been observed with lithium chloride, piperazine, piperidine and ethylenediamine. Methylamine, guanidine and hexamethylenetetramine were ineffective. Hypertonic solutions of glucose, sodium sulphate and sodium chloride cause a diuresis with an increase in the output of urate. Theophylline, "euphylline," and to a lesser extent caffeine, adrenaline and colchicine, act similarly. Theobromine and the salicylates are without definite effect.

The general conclusion is drawn that any substance which will cause a diuresis in the cockerel will increase the output of urate and tend to make the urine alkaline. No substance has been found to increase the output of uric acid by allowing a concentration of urate greater than the normal.