The lipid-mobilizing effect of atrial natriuretic peptide is unrelated to sympathetic nervous system activation or obesity in young men

We recently demonstrated that natriuretic peptides and especially the atria l natriuretic peptide (ANP) are powerful lipolytic agents on isolated human fat cells. To search for a possible influence of obesity on ANP responsive ness, we compared the lipolytic effects of human ANP (h-ANP) on isolated su bcutaneous abdominal adipose tissue (SCAAT) fat cells from young healthy le an and obese men, The lipid-mobilizing effects of an intravenous infusion o f h-ANP was studied, as well as various metabolic and cardiovascular parame ters that were compared in the same subjects. h-ANP (50 ng/min/kg) was infu sed iv for 60 min. Microdialysis probes were inserted in SCAAT to measure m odifications of the extracellular glycerol concentrations during h-ANP infu sion. Spectral analysis of blood pressure and heart rate oscillations that were recorded using digital photoplethysmography were used to assess change s in autonomic nervous system activity. h-ANP induced a marked and similar increase in glycerol and nonesterified fatty acids, and a weak increase in insulin plasma levels in lean and obese men, Plasma norepinephrine concentr ations rose similarly during h-ANP infusion in lean and obese men. The effe cts of h-ANP infusion on the autonomic nervous system were similar in both groups, with an increase in the spectral energy of the low-frequency band o f systolic blood pressure variability and a decrease in the spectral energy of the high-frequency band of heart rate. In SCAAT, h-ANP infusion increas ed extracellular glycerol concentration and decreased blood flow similarly in both groups, The increase in extracellular glycerol observed during h-AN P infusion was not modified when 0.1 mM propranolol was added to the microd ialysis probe perfusate to prevent beta -adrenoceptor activation. These dat a show that ANP is a potent lipolytic hormone independent of the activation of the sympathetic nervous system, and that obesity did not modify the lip id-mobilizing effect of ANP in young obese subjects.