Abstract

Objective. Atrial natriuretic peptide (ANP) regulates arterial blood pressure. In addition, ANP has recently been shown to promote human adipose tissue lipolysis through cGMP-mediated hormone sensitive lipase activation. We hypothesized that ANP increases postprandial free fatty acid availability and energy expenditure, while decreasing arterial blood pressure.

Research Design and Methods. We infused human ANP (25 ng/kg/min) in 12 men (age 32±0.8 years, body mass index 23.3±0.4 kg/m²) before, during, and 2 h after ingestion of a standardized high-fat test meal in a randomized, double blind, cross-over fashion. Cardiovascular changes where monitored by continuous ECG and beat-by-beat blood pressure recordings. Metabolism was monitored through venous blood sampling, intramuscular and subcutaneous abdominal adipose tissue microdialysis, and indirect calorimetry.

Results. ANP infusion decreased mean arterial blood pressure by 4 mmHg during the postprandial phase (p<0.01 vs placebo). At the same time, ANP induced lipolysis systemically (p<0.05 vs placebo) and locally in subcutaneous abdominal adipose tissue (p<0.0001 vs placebo), leading to a 50% increase in venous glycerol (p<0.01) and free fatty acid (FFA) (p<0.05) concentrations compared to placebo. The increase in FFA availability with ANP was paralleled by a 15% increase in lipid oxidation rates (p<0.05 vs placebo), driving a substantial increase in postprandial energy expenditure (p<0.05 vs placebo).

Conclusions. Our data identifies the ANP system as a novel pathway regulating postprandial lipid oxidation, energy expenditure, and concomitantly arterial blood pressure. The findings could have therapeutic implications.