Stop flow analysis of renal function in the monkey

¹ Departments of Physiology and Pharmacology, School of Medicine, The University of Michigan, Ann Arbor, Michigan

Stop flow analysis has been used to study renal function in the macaque monkey. Mannitol diuresis produced excretion of 58–70% of filtered water and 22–34% of filtered sodium. An absence of water and sodium reabsorption from the proximal tubule during ureteral occlusion was observed in three of four experiments, suggesting that this portion of the monkey nephron cannot transport sodium as efficiently as the canine proximal tubule during osmotic diuresis or that it is less permeable to water. Creatinine secretion was observed and localized to the same portion of the proximal tubule which secretes PAH. Inorganic phosphate and glucose reabsorption also occurred in the proximal tubule. Sodium, chloride, and potassium stop flow patterns were identical to those reported for the dog. Chlorothiazide caused an inhibition of distal tubular sodium reabsorption and an enhancement of potassium secretion in the distal nephron. Proximal tubular activity of the drug could not be evaluated.