Sympathetic activity and response to ACE inhibitor (enalapril) in normotensive obese and non-obese subjects.

BACKGROUND

Angiotensinogen has been proposed as a possible link between obesity and hypertension because the adipocyte produces angiotensinogen and contains the enzymes required for its conversion. Moreover, sympathetic overactivity has been reported in obese subjects. The aim of this study was to compare heart sympathetic activation and serum angiotensinogen levels in obese and non-obese normotensive subjects, their relationship, and the effect of a drug that modifies the renin-angiotensin system.

METHODS

Serum angiotensinogen, leptin, lipids, glucose, and insulin levels were measured and 24-h electrocardiograph monitoring was carried out in 41 (20 non-obese and 21 obese) volunteers before and after administration of 5 mg enalapril twice/day for 7 days.

RESULTS

Obese subjects had higher values than non-obese subjects for % body fat (35.1+/-4.6 vs. 30.5+/-5.2; p=0.005), triglycerides (1.93+/-0.9 vs. 1.25+/-0.7 g/L, p=0.002), insulin (114.8+/-82.5 vs. 45.9+/-22.2 pmol/L), leptin (31.4+/-20.4 vs. 14.1+/-11.2 ng/mL, p=0.002), and LF/HFn index (4.3+/-2.9 vs. 2.2+/-1.3, p<0.005). Enalapril increased angiotensinogen levels only in the non-obese group (4.2+/-3.9 vs. 9.7+/-5.4 ng/mL, p=0.001) and diminished the LF/HFn index (4.3+/-2.9 vs. 3.0+/-1.4, p=0.007) in the group of obese subjects. There was no association between angiotensinogen levels and sympathetic activity.

CONCLUSIONS

Higher level of sympathetic activity was found in normotensive obese as compared with non-obese subjects. Enalapril treatment reduced heart sympathetic activity in obese subjects but did not change angiotensinogen levels.