Abstract 469: Influences of Dietary Weight Reduction on the Atrial Natriuretic Peptide System in Obese Subjects

Abstract

In obese individuals, reduced atrial natriuretic peptide (ANP) bioavailability appears to promote arterial hypertension and type 2 diabetes likely through direct metabolic actions. Mid-regional pro-ANP is cleaved off during ANP processing, thus, serving as ANP release marker. We hypothesized that dietary weight reduction improves ANP release. In 75 overweight and obese women and men who had lost >5% body weight during six months hypocaloric dieting (-9.1±3.8 kg), we analyzed venous mid-regional pro-ANP and natriuretic peptide receptor (NPR) expression in abdominal subcutaneous adipose tissue before and after the intervention. Participants underwent ambulatory blood pressure (ABPM) monitoring and cardiac magnetic resonance imaging. ABPM decreased from 118±9/73±7 to 115±9/71±6 mm Hg and left ventricular mass from 92±20 to 86±19 g (p<0.05 for all). End-diastolic and end-systolic volumes remained unchanged. Mid-regional pro-ANP plasma concentrations did not respond to weight loss (before: 51±24 pmol/; after 53± 24 pmol/l) and increased similarly during exercise testing. Adipose NPR-A mRNA expression remained unchanged whereas NPR-C receptor mRNA decreased from 1.2±0.7 to 1.0±0.5 (p<0.05). Our data suggest that dietary weight loss does not augment ANP release in overweight and obese subjects. However, weight loss could improve ANP bioavailability through decreased clearance. Possible mechanisms are reduced fat mass and reduced expression of adipose tissue ANP scavenger receptor NPR-C.