On the mechanism of inhibition in fluid reabsorption by the renal proximal tubule of the volume-expanded rat

BM Brenner, JL Troy, TM Daugharty… - The Journal of …, 1971 - Am Soc Clin Investig
BM Brenner, JL Troy, TM Daugharty, IF Ueki, DP Nicholas, CF Wong
The Journal of Clinical Investigation, 1971Am Soc Clin Investig
We undertook to determine the extent to which the inhibition in absolute proximal fluid
reabsorption in response to expansion of extracellular volume with noncolloid-containing
solutions is the result of concomitant reductions in postglomerular (efferent arteriolar) protein
concentration. Selective elevation of efferent arteriolar oncotic pressure in volume-expanded
rats (Ringer's 10% body weight) to levels slightly in excess of normal by microperfusion with
9-10% albumin-Ringer's solution nearly completely reversed the inhibition in absolute and …
We undertook to determine the extent to which the inhibition in absolute proximal fluid reabsorption in response to expansion of extracellular volume with noncolloid-containing solutions is the result of concomitant reductions in postglomerular (efferent arteriolar) protein concentration. Selective elevation of efferent arteriolar oncotic pressure in volume-expanded rats (Ringer's 10% body weight) to levels slightly in excess of normal by microperfusion with 9-10% albumin-Ringer's solution nearly completely reversed the inhibition in absolute and fractional reabsorption in adjacent proximal tubules. In contrast, during similar microperfusion with a 6-7% albumin solution, no increase in proximal reabsorption was measured. We interpret these findings to indicate that the bulk of the inhibition in absolute proximal reabsorption in response to volume expansion with colloid-free solutions is causally mediated by the accompanying parallel decline in postglomerular vascular protein concentration.
The Journal of Clinical Investigation