Micropuncture Study of Water Reabsorption and PAH Secretion in Urea Diuresis in Rats.

Abstract

Summary Inulin and PAH concentrations and osmolalities were determined in samples of tubular fluid collected from surface convolutions of rat kidneys during urea diuresis. F/P inulin ratios averaged 1.6 for the proximal tubule, 2.9 for the distal convolution and 21.7 for the ureteral urine, all significantly lower than in nondiuretic rats. Net PAH secretion appeared to be confined to the proximal tubule and could not be demonstrated in other parts of the nephron.