Because of recent conflicting results, micropuncture studies were performed to clarify the respective role of the distal convoluted tubule and collecting duct in the regulation of urinary potassium excretion. Five groups of Sprague-Dawley rats were studied: group I, hydropenia (n = 10); group II, Ringer loading (n = 7); group III, acute KC1 loading (n = 6); group IV, mannitol diuresis (n = 6); group V, KC1 infusion during mannitol diuresis (n = 7). Early and late distal tubules were identified with intravenous injections of lissamine green. In each animal net secretion of potassium occurred along the distal convoluted tubule, and a direct relationship between distal tubular flow rate and potassium secretion was observed. The magnitude of potassium secretion at high distal tubular flow rates was dependent on the model studied. Potassium transport beyond the distal tubule was evaluated by comparing end distal potassium delivery and fractional potassium excretion. At low urinary flow rates net reabsorption was observed, whereas at higher flow rates no net transport occurred. Thus, flow rate along the collecting duct may be a major determinant of urinary potassium excretion.
The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.