AMMONIA FORMATION IN THE AMPHIBIAN KIDNEY

Abstract

[longdash]An ultramicro modification of the direct Nessleri-zation method for ammonia determinations is descr. which, by permitting quantitative analyses upon as little as 0.1 cu. mm. of fluid, has made possible the analysis of fluid collected from glomeruli and various portions of single renal tubules of the amphibian kidney. Ammonia does not appear within the tubule lumen in appreciable amts. until the latter two-thirds of the distal tubule. Within this region, and possibly also in the early part of the collecting duct, the ammonia conc. gradually increases until it approximates that of ureteral urine. This portion of the nephron constitutes the site of ammonia formation. The source of this ammonia is probably a precursor which is stored within the tubule cells, but the expts. did not resolve the question whether this substance is urea or an amino acid.