Stop-flow localization of renal tubular excretion of tetraethylammonium

¹ Department of Physiology, State University of New York, Upstate Medical Center, Syracuse, New York

In stop-flow experiments TEA appeared at about the same proximal level of the tubule as PAH following intravenous or intra-arterial injection during ureteral occlusion. Increasing the duration of occlusion following injection lead to a progressively more distal appearance of TEA and PAH. This movement could be a result of pulsation of the column of fluid in the lumen with resultant slurring of the concentration borders; or of diffusion of intraluminal TEA and PAH from the area of secretion to neighboring low concentration sites; or of distal reabsorption of water with consequent movement of the column.