The effect of saline infusion on proximal sodium reabsorption was compared in normal dogs and in dogs with acute or chronic partial thoracic vena cava obstruction. After acute vena cava obstruction, proximal fractional sodium reabsorption rose by 74%. During continued caval obstruction, saline loading strikingly reduced proximal reabsorption but sodium excretion remained minimal. In chronic caval dogs, saline loading reduced proximal fractional sodium reabsorption by 31% but sodium excretion in the micropunctured kidney was only 41 μEq/min. After saline infusion in normal dogs, proximal fractional sodium reabsorption fell 39% while unilateral sodium excretion rose to 584 μEq/min.
R. Brewer Auld, Edward A. Alexander, Norman G. Levinsky