Abstract

autonomic function with metabolic abnormalities in childhood obesity. Obesity. 2007;15:1164–1171. Objective: The objective was to examine cardiovascular autonomic (cANS) function and its potential relationships with leptin resistance, insulin resistance, oxidative stress, and inflammation in a pediatric sample with varying levels of obesity. Research Methods and Procedures: Participants were nor-mal-weight (NW; BMI85th percentile, 6 male, 4 female), overweight (OW; 85th percentile BMI 95th percentile, 6 male, 4 female), and obese children (OB; BMI 95th percentile, 6 male, 10 female) who had cANS function assessed via heart rate variability (HRV) methods during resting conditions. Standard time-domain and frequency-domain measures [high-frequency normalized units (HFnu; measure of parasympathetic nervous system activity) and low frequency:high-frequency ratio (LF:HF; overall sympa-thovagal balance)] of HRV were calculated. Fasting blood samples were drawn for measurement of glucose, insulin, lipids, 8-isoprostane, leptin, soluble leptin-receptor (sOB-R), C-reactive protein (CRP), interleukin-6 (IL-6), and tu-mor necrosis factor- (TNF-). Results were reported as mean standard error of the mean. Results: OB had significantly elevated LF:HF and de-creased HFnu when compared with NW (p 0.05), but no differences between OW and NW were observed. Measures of HRV were significantly related to leptin, insulin resis-tance, 8-isoprostane, and CRP (p 0.05), but these rela-tionships were not significant after adjustment for fat mass. Discussion: When compared with NW, OB but not OW children are characterized by cANS dysfunction and in-creased leptin, insulin resistance, oxidative stress, and in-flammation (CRP). The relationships between these factors seem to be dependent on quantity of fat mass and/or other factors associated with being obese