Abstract
Summary
Experiments were performed to evaluate the relative contribution of changes in proximal and distal tubular reabsorption to the natriuresis induced by vasodilator–vasopressor combinations (vasoactive drugs). In normal dogs preloaded with hyperoncotic albumin, vasoactive drugs induced natriuresis without altering PFSR, nephron filtration rate or calculated distal delivery of filtered sodium. Thus, these agents can increase sodium excretion by inhibiting distal reabsorption in the absence of a proximal effect. In saline-loaded dogs with thoracic vena caval constriction, the natriuresis induced by vasoactive drugs was associated with a fall in PFSR and an increase in calculated distal delivery. In these edematous dogs, proximal and distal inhibition both appear to contribute to the increase in sodium excretion.
These studies were supported by NIH Grant Nos. AM-11793, AM-14004, AM-5209 and HE-07299, and the Nova Scotia Heart Foundation Grant-in-Aid No. X67-22. L. M. B. was a Lilly International Fellow and was supported by a grant from the Eli Lilly Co. and by the General Research Support Grant to University Hospital. We are grateful for the expert technical assistance of Miss Eileen McNamara and Miss Greta Markowitz.
Get full access to this article
View all access options for this article.