Abstract
Individuals with high plasma norepinephrine (NE) levels at rest have a smaller reduction in resting energy expenditure (REE) following β-adrenergic blockade. If this finding extends to the response to a meal, it could have important implications for the role of the sympathetic nervous system in energy balance and weight gain. We hypothesized high muscle sympathetic nerve activity (MSNA) would be associated with a low sympathetically mediated component of energy expenditure following a meal. Fourteen young, healthy adults completed two visits randomized to continuous saline (control) or intravenous propranolol to achieve systemic β-adrenergic blockade. Muscle sympathetic nerve activity and REE were measured (indirect calorimetry) followed by a liquid mixed meal (Ensure). Measures of energy expenditure continued every 30 min for 5 h after the meal and are reported as an area under the curve (AUC). Sympathetic support of energy expenditure was calculated as the difference between the AUC during saline and β-blockade (AUCP ropranolol–AUCS aline, β-REE) and as a percent (%) of control (AUCP ropranolol÷AUCS aline × 100). β-REE was associated with baseline sympathetic activity, such that individuals with high resting MSNA (bursts/100 heart beats) and plasma NE had the greatest sympathetically mediated component of energy expenditure following a meal (MSNA: β-REE R = −0.58, P = 0.03; %REE R = −0.56, P = 0.04; NE: β-REE R = −0.55, P = 0.0535; %REE R = −0.54, P = 0.0552). Contrary to our hypothesis, high resting sympathetic activity is associated with a greater sympathetically mediated component of energy expenditure following a liquid meal. These findings may have implications for weight maintenance in individuals with varying resting sympathetic activity.
Original language | English (US) |
---|---|
Article number | e13389 |
Journal | Physiological reports |
Volume | 5 |
Issue number | 16 |
DOIs | |
State | Published - Aug 2017 |
Keywords
- propranolol
- thermic effect of food
- β-adrenergic
ASJC Scopus subject areas
- Physiology
- Physiology (medical)