The excretion of uric acid by the kidney

Abstract

The excretion of uric acid by the kidney has played an important part in the investigations and speculations concerning the mechanism of urinary secretion. The microscopic investigation of the kidney, after the injection of uric acid or the administration of large amounts of purines, has shown the presence of granules of uric acid in the cells of the convoluted tubules and a precipitate of this substance in the lumen of the tubules (Heidenhain, Nussbaum, Ebstein, Nikolaier, Sauer, Minkowski, Eckert and others) (1). These appearances have been held to support Heidenhain’s theory that the convoluted tubules are the seat of secretion of uric acid. Other observers, and especially Cushny (2) in his presentation of the modern theory of secretion, do not accept this interpretation, but regard the granules as due to a process of absorption of the substance from the dilute filtrate formed by the glomeruli and passing down the tubules. According to Folin (3) the kidney of the dog is able to store considerable amounts of injected uric acid and to return it to the blood stream later. This observer described a very rapid disappearance of injected uric acid from the blood, which he ascribes to oxidation in the blood itself as it passes through the tissues. A more detailed discussion of Folin’s results will be given later.