6533b838fe1ef96bd12a480a

RESEARCH PRODUCT

D-Glucose and fluid reabsorption in proximal surface tubule of the rat kidney

subject

description

Hexose reabsorption in the kidney was investigated by microperfusion of proximal cortical rat nephrons with Ringer's solution containingD-glucose (2.5, 5.0 and 18.0 mM/l), 3-O-methylD-glucose (4.5 mM/l) orD-fructose (18.0 mM/l) at perfusion rates of 20 or 40×10−6 ml/min. Inulin was used as a reference for fluid reabsorption. 1. The fraction of fluid reabsorbed was independent of the glucose concentration but it decreased when the perfusion rate increased from 20–40×10−6 ml/min. 2. At 18.0 mM/l the % glucose reabsorption was equal to the % fluid reabsorption. This equality was independent of the perfusion rate, (20 or 40×10−6 ml/min), indicating 1:1 coupling with net isotonic fluid reabsorption. 3. At 2.5 mM/l the % glucose reabsorption was greater than the % fluid reabsorption, indicating predominance of an active component to theD-glucose transport. 4. 3-O-methylD-glucose was reabsorbed at one third the rate ofD-glucose. There was no reabsorption ofD-fructose at the concentration used. Since neither of the latter two sugars showed an increment in reabsorption proportional to changes in net fluid movement, we postulate that specificity for glucose reabsorption occurs prior to the site of coupling with fluid flow.