Metabolic effects of an increase of sympathetic activity in healthy humans.
OBJECTIVE
To determine the metabolic effects of catecholamines released at sympathetic nerves ending in the postabsorptive and postprandial states.


METHODS
Sympathetic activity was acutely increased by lower body negative pressure (LBNP; -15 mmHg) on two occasions in a group of eight healthy volunteers: (1) in the postabsorptive state; and (2) after glucose ingestion.


METHODS
Plasma norepinephrine concentrations were determined by HPLC and energy expenditure and substrate oxidation rates were assessed with indirect calorimetry.


RESULTS
After glucose, LBNP increased plasma norepinephrine by 27% and lipid oxidation by 72% and decreased glucose oxidation by 14%. Energy expenditure was not altered. In the postabsorptive state, LBNP increased plasma norepinephrine by 34%, but had no significant effect on energy or substrate metabolism.


CONCLUSIONS
In healthy humans, LBNP-induced activation of the sympathetic nervous system decreases glucose oxidation and increases lipid oxidation after oral glucose, but does not quantitatively affect energy expenditure.
Tappy
L
L
Institute of Physiology, Faculty of Medicine, Lausanne University, Switzerland.
Girardet
K
K
Schwaller
N
N
Vollenweider
L
L
Jéquier
E
E
Nicod
P
P
Scherrer
U
U
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002153:Calorimetry, Indirect; D002395:Catecholamines / Q000378:metabolism / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D009638:Norepinephrine / Q000097:blood; D013564:Sympathetic Nervous System / Q000378:metabolism / Q000502:physiology*
D001786:Blood Glucose; D002395:Catecholamines; D005947:Glucose; D009638:Norepinephrine; D004837:Epinephrine