Evidence for a proximal site of action of atrial natriuretic peptide in man.

The site of action of atrial natriuretic peptides (ANP) in man remains uncertain. In this study the attention was focused on the proximal tubule. Three markers of the proximal tubular reabsorption were used as a tool: lithium, amino acids and beta 2-microglobulin. The reabsorption of these three substances was decreased during ANP infusions in 3 normal sodium-replete male volunteers. These findings suggest that ANP not only decreases distal sodium reabsorption, but also proximal fractional tubular sodium reabsorption in man.