Effect of rapid and transitory changes in blood and urine pH on NH4 excretion

Abstract

The Chinard technique of close arterial injection has been adapted to permit a closer study of the relationship of pH to ammonium excretion. NaHCO₃, Na₄Fe(CN)₆, HCl, and creatinine hydrochloride solutions were injected into a renal artery of a dog undergoing osmotic diuresis while 15-sec serial urine and renal venous blood samples were being collected. Because of the difference in transit time between blood and urine the effect of the alteration in blood pH upon ammonium excretion could be seen before the filtered portion of the injection reached the urine. Thus NaHCO₃ in the blood raised urine ammonium concentration while urine pH remained relatively constant. Later as NaHCO₃ appeared in the urine, pH rose and urine ammonium concentration fell. Na₄Fe(CN)₆, which decreased blood pH, produced opposite effects. HCl and creatinine hydrochloride caused an immediate fall in both urine pH and ammonium concentration which persisted during the appearance of the injection in the urine. The results of these experiments are interpreted in terms of the theory of nonionic diffusion.