Effects of pentolinium on sodium excretion in dogs with constriction of the vena cava

Abstract

In seven adrenalectomized dogs with constriction of the thoracic inferior vena cava, treated with cortisone and deoxycorticosterone, blockade of the autonomic ganglia increased mean sodium excretion from 9 to 56 [mu]Eq/min. In a second series of clearances, blockade plus infusion of 2 liters normal saline increased mean sodium excretion from 14 to 165 [mu]Eq/min. whereas infusion alone increased mean sodium excretion from 6 to 32 [mu]Eq/min. In both series of clearances, the increase in sodium excretion occurred despite decreases in arterial pressure and, in some cases, decreases in filtered sodium. The results indicate that blockade of the autonomic nervous system can increase sodium excretion in dogs with ascites. This increase in sodium excretion with blockade occurs partly as a result of a decrease in the tubular reabsorption of sodium. The studies support the hypothesis that a sustained increase in autonomic activity prevents escape from the effects of sodium-retaining steroids, thereby contributing to sustained retention of sodium and water.