Micropuncture Study of Net Transtubular Movement of Urea and Water in Rats Expanded with Isotonic Saline 1

Abstract

Summary

Net transtubular movement of urea and water was studied in rats made diuretic by infusion of a volume of isotonic saline solution equivalent to 10% of their body weight. The major site of urea reabsorption was the proximal tubule and there was little urea loss from more distal parts of the nephron. There was no evidence of addition of urea to tubular fluid flowing through the loop of Henle. Throughout the nephron the percentage of filtered water remaining varied exponentially with transit time.