Potassium secretion and reabsorption in distal nephron

¹ Department of Physiology, School of Medicine, University of Michigan, Ann Arbor, Michigan

Potassium transport in the distal nephron has been investigated, using stop flow and slow flow techniques. Results indicate that potassium is secreted in the collecting duct and far distal tubule, and that sodium must be present for this secretion to occur. The usual stop flow distal potassium dip would appear to be a true site of active potassium reabsorption. This reabsorptive area includes the collecting duct and distal tubule and is completely coextensive with the sodium reabsorptive area. Potassium reabsorption and secretion can occur simultaneously in the collecting duct and far distal tubule. This phenomenon explains the observation (confirmed in this study) that the stop flow potassium peak diminishes as duration of occlusion is increased.