Effects of nitric oxide synthesis inhibition on the atrial natriuretic peptide system

The present study was aimed at investigating whether nitric oxide (NO) has a modulatory effect on the atrial natriuretic peptide (ANP) system. The atrial tissue expression of ANP mRNA was determined in rats treated with an inhibitor of NO synthesis, N(G)-nitro-L-arginine methyl ester (L-NAME), for 4 weeks. Measurements of ANP peptides and NO metabolites in the plasma and atria were also taken. The blood pressure was increased by the treatment with L-NAME (40 mg l(-1)drinking water). The atrial expression of ANP mRNA was increased. Atrial natriuretic peptides were also increased, while NO metabolites decreased in the plasma and atrial tissue. An antihypertensive treatment with losartan reversed the blood pressure to the control level. However, the atrial expression of ANP mRNA was not affected but remained at an increased level. Accordingly, the plasma ANP was elevated and NO decreased. Supplementation with L-arginine, the substrate to NO synthase, prevented the changes induced by L-NAME. These results suggest that the synthesis and release of ANP be regulated by local release of NO with a transcriptional inhibition.