Secretion of potassium and acidification in collecting ducts of mammalian kidney

¹ Department of Physiology, Cornell University Medical College, New York City

As part of an investigation of the site of potassium secretion, potassium and inulin clearances were measured simultaneously in golden hamsters during infusion of KCl, acetazoleamide and sodium sulfate. Potassium clearance exceeded that of inulin, indicating that K must have been secreted into the tubular fluid. Utilizing the microcatheterization technique, tubular fluid was drawn from the collecting duct system of the golden hamster during sulfate diuresis. In the first series of experiments carried out during KCl infusion, evidence was obtained of a contribution by the distal portion of the collecting duct system to K secretion. In a second series, without KCl infusion, pH measurements demonstrated that acidification occurs in the same segment, confirming results obtained by previous investigators. However, both secretion of potassium ions and of hydrogen ions cannot be confined completely to the distal collecting duct system under conditions of sulfate diuresis, but must also occur in more proximal parts of the nephron.