Journal article
Dissociation Between Sympathetic Nerve Traffic and Sympathetically Mediated Vascular Tone in Normotensive Human Obesity
Hypertension (Dallas, Tex. 1979), Vol.52(4), pp.687-695
10/2008
DOI: 10.1161/HYPERTENSIONAHA.107.109603
PMCID: PMC4222518
PMID: 18695151
Abstract
Obesity increases the risk of hypertension and its cardiovascular complications. This has been partly attributed to increased sympathetic nerve activity, as assessed by microneurography and catecholamine assays. However, increased vasoconstriction in response to obesity-induced sympathoactivation has not been unequivocally demonstrated in obese subjects without hypertension. We evaluated sympathetic α-adrenergic vascular tone in the forearm by brachial arterial infusion of the α-adrenoreceptor antagonist phentolamine (120 μg/min) in normotensive obese (daytime ambulatory arterial pressure123±1/77±1 mm Hg; body mass index35±1 kg/m) and lean (daytime ambulatory arterial pressure123±2/77±2 mm Hg; body mass index22±1 kg/m) subjects (n=25 per group) matched by blood pressure, age, and gender. Microneurographic sympathetic nerve activity to skeletal muscle was significantly higher in obese subjects (30±3 versus 22±1 bursts per minute; P=0.02). Surprisingly, complete α-adrenergic receptor blockade by phentolamine (at concentrations sufficient to completely inhibit norepinephrine and phenylephrine-induced vasoconstriction) caused equivalent vasodilatation in obese (−57±2%) and lean subjects (−57±3%; P=0.9). In conclusion, sympathetic vascular tone in the forearm circulation is not increased in obese normotensive subjects despite increased sympathetic outflow. Vasodilator factors or mechanisms occurring in obese normotensive subjects could oppose the vasoconstrictor actions of increased sympathoactivation. Our findings may help to explain why some obese subjects are protected from the development of hypertension.
Details
- Title: Subtitle
- Dissociation Between Sympathetic Nerve Traffic and Sympathetically Mediated Vascular Tone in Normotensive Human Obesity
- Creators
- Alexei Agapitov - From the Institute for Clinical and Translational Science and Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa CityMarcelo CorreiaChristine SinkeyWilliam Haynes
- Resource Type
- Journal article
- Publication Details
- Hypertension (Dallas, Tex. 1979), Vol.52(4), pp.687-695
- Publisher
- American Heart Association, Inc
- DOI
- 10.1161/HYPERTENSIONAHA.107.109603
- PMID
- 18695151
- PMCID
- PMC4222518
- ISSN
- 0194-911X
- eISSN
- 1524-4563
- Language
- English
- Date published
- 10/2008
- Academic Unit
- Endocrinology and Metabolism; Internal Medicine
- Record Identifier
- 9984094553902771
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