OBJECTIVE: To investigate changes in sympathetic nervous system function in obesity. DESIGN: Cross-sectional clinical study. SUBJECTS: 18 middle-aged obese patients (43-55 years, BMI > 33 kg/m2) and 26 age- and sex-matched normal-weight controls (44-56 years, BMI < 26 kg/m2). MEASUREMENTS: Post-synaptic sympathetic response studied by power spectral analysis of heart rate variability at rest and during sympathetic stimulus obtained through passive head-up tilt. Spectral analysis comprised two frequency domain components: high-frequency power (HF), reflecting parasympathetic activity and low-frequency power (LF), in particular the LF: HF ratio, reflecting sympathetic function. Pre-synaptic sympatho-adrenal function was assessed by measurement of 8.00 am plasma noradrenaline. RESULTS: Obese patients had significantly lower spectral indexes of sympathetic response and higher spectral markers of parasympathetic activity than nonobese subjects both at rest (25.9 +/- 3.5 vs 38.6 +/- 1.7 LF NUs, P < 0.001) and after tilt (0.98 +/- 0.40 vs 2.30 +/- 0.39 LF: HF, P < 0.05; 62.7 +/- 6.9 vs 41.1 +/- 4.9 HF NUs, P < 0.05). By contrast, the obese subjects had higher noradrenaline levels (289.32 +/- 27.40 vs 159.80 +/- 19.20 pg/ml, P < 0.001). No relation was found between these neuroautonomic indexes and body mass index. CONCLUSION: Obese subjects seem to have increased pre-synaptic sympatho-adrenal function but a depressed end-organ cardiovascular response.
OBJECTIVE: To investigate changes in sympathetic nervous system function in obesity. DESIGN: Cross-sectional clinical study. SUBJECTS: 18 middle-aged obesepatients (43-55 years, BMI > 33 kg/m2) and 26 age- and sex-matched normal-weight controls (44-56 years, BMI < 26 kg/m2). MEASUREMENTS: Post-synaptic sympathetic response studied by power spectral analysis of heart rate variability at rest and during sympathetic stimulus obtained through passive head-up tilt. Spectral analysis comprised two frequency domain components: high-frequency power (HF), reflecting parasympathetic activity and low-frequency power (LF), in particular the LF: HF ratio, reflecting sympathetic function. Pre-synaptic sympatho-adrenal function was assessed by measurement of 8.00 am plasma noradrenaline. RESULTS:Obesepatients had significantly lower spectral indexes of sympathetic response and higher spectral markers of parasympathetic activity than nonobese subjects both at rest (25.9 +/- 3.5 vs 38.6 +/- 1.7 LF NUs, P < 0.001) and after tilt (0.98 +/- 0.40 vs 2.30 +/- 0.39 LF: HF, P < 0.05; 62.7 +/- 6.9 vs 41.1 +/- 4.9 HF NUs, P < 0.05). By contrast, the obese subjects had higher noradrenaline levels (289.32 +/- 27.40 vs 159.80 +/- 19.20 pg/ml, P < 0.001). No relation was found between these neuroautonomic indexes and body mass index. CONCLUSION:Obese subjects seem to have increased pre-synaptic sympatho-adrenal function but a depressed end-organ cardiovascular response.
Authors: Luenda E Charles; Cecil M Burchfiel; Khachatur Sarkisian; Shengqiao Li; Diane B Miller; Ja K Gu; Desta Fekedulegn; John M Violanti; Michael E Andrew Journal: Am J Hum Biol Date: 2014-10-01 Impact factor: 1.937
Authors: Jill A Kanaley; Tracy Baynard; Ruth M Franklin; Ruth S Weinstock; Styliani Goulopoulou; Robert Carhart; Robert Ploutz-Snyder; Arturo Figueroa; Bo Fernhall Journal: Metabolism Date: 2007-06 Impact factor: 8.694