Stop-flow analysis of renal reabsorption and excretion of sulfate in the dog

Abstract

Utilizing the stop-flow technique, the site of reabsorption of inorganic sulfate has been localized in the proximal part of the nephron of the dog. Sulfate is most avidly reabsorbed in that portion of the proximal tubule which most actively secretes PAH. No evidence of secretion of inorganic sulfate in any part of the nephron or of reabsorption of inorganic sulfate in more distal parts of the nephron has been found. However, the infusion of large quantities of sodium sulfate activates the mechanisms of urinary acidification and of potassium and ammonia secretion located in the terminal nephron. This activation is similar to that induced by sodium phosphate and by sodium ferrocyanide and is interpreted as resulting from the presence of unreabsorbed anion in distal tubules and collecting ducts. The infusion of glycine specifically stimulates ammonia secretion.