Different responses of atrial natriuretic peptide secretion and its receptor density to salt intake in rats.

This study investigated whether high-salt intake influences atrial natriuretic peptide (ANP) system, atrial content, and release rate of ANP as well as receptor density in the kidney were measured in salt intake rats. Male Sprague-Dawley rats received either 0.9% or 2% salt in their drinking water for 10 days. The stretch-induced ANP secretion from isolated perfused non-beating left atria was accentuated, and the production of cGMP by ANP in renal cortical tissue membranes were pronounced in rats exposed to 0.9% salt for 10 days but not in rats exposed to 2% salt. The levels of ANP receptor density and expression in renal cortex were decreased in 2% salt intake rats but not in 0.9% salt intake rats. No significant differences in atrial and plasma concentrations of ANP and water balance were observed in both salt intakes. Therefore, these results suggest that atrial ANP secretion and its binding sites in the kidney may respond differently to ingested salt concentrations in rats.