Volume-expansion natriuresis: nephron function beyond the superficial late distal tubule
Bengele, H.H.; Mcnamara, E.R.; Alexander, E.A.
American Journal of Physiology 232(6): F566-F570
1977
ISSN/ISBN: 0002-9513 PMID: 879291 Document Number: 122732
Micropuncture studies in rats were performed during chronic and/or varying degrees of acute saline loading. Addition of Na beyond the superficial late distal tubule was demonstrated in rats acutely expanded to 15% of body wt with or without prior chronic saline ingestion, but Na reabsorption occurred in animals expanded to 10% of body wt or less. Collecting duct Na reabsorption appeared to be inversely related to the degree of volume expansion. Recovery of late distal tubular injections of 22Na was virtually complete in the rats expanded to 15% body wt, while 67% was recovered after 10% body wt expansion and 41% in chronic saline-drinking rats. Na transport beyond the superficial late distal tubule is regulated by the degree of volume expansion. The net addition of Na is a function of the degree of acute volume expansion.