Abstract 14113: Parallel Induction of Circulating Fatty Acid Binding Protein 4 and Norepinephrine During Exercise: Implication for a Novel Biomarker for Sympathetic Nervous Activity
Background: The sympathetic nervous system plays a central role in the regulation of cardiovascular and metabolic response in a variety of pathophysiological states. Fatty acid binding protein 4 (FABP4) functions as an intracellular lipid chaperone in adipocytes. Our recent studies show that FABP4 is secreted from adipocytes by β3-adrenergic stimulation and circulating FABP4 levels are robustly elevated in patients with acute myocardial infarction and ventricular tachyarrhythmia which are characterized by adrenergic overdrive. However, little is known about the physiological change in serum FABP4 levels during exercise.
Methods and Results: Thirty one healthy volunteers (19 male/12 female, age 24.4±3.3, body mass index (BMI) 21.4±2.8 kg/m2) underwent cardiopulmonary exercise testing on a cycle ergometer up to the workload levels below and above anaerobic threshold, a low- and high-intensity exercise, respectively. Serial blood samplings were performed; before exercise, immediately after exercise, 10 min, 20 min after exercise. Samples were analyzed for catecholamines (norepinephrine, epinephrine, dopamine) and FABP4. High-intensity exercise significantly increased serum FABP4 level as well as all three catecholamines levels, while low-intensity exercise increased little, if any, FABP4 and catecholamines from baseline. Time course of serum FABP4 levels was similar to that of norepinephrine and epinephrine; they peaked at immediately after exercise and declined to the baseline levels by 10 min after exercise. While baseline FABP4 levels were variable dependent upon BMI, percent change from baseline in FABP4 levels was comparable irrespective of BMI, and was significantly correlated with that in norepinephrine. Stepwise regression analysis revealed that percent change from baseline in FABP4 was strongly correlated with that in norepinephrine (beta 0.733, p<0.001).
Conclusions: Circulating FABP4 and norepinephrine concentrations rapidly increase in parallel during high-intensity exercise. Given that an increment of plasma norepinephrine may be an index of adrenergic overdrive and may have effects on FABP4 secretion through adipocyte lipolysis, serum FABP4 may serve as a biomarker for augmented sympathetic nervous activity.
Author Disclosures: T. Iso: None. H. Sunaga: None. N. Ohshima: None. H. Haruyama: None. N. Furukawa: None. H. Matsui: None. T. Yokoyama: None. M. Kurabayashi: None.
- © 2016 by American Heart Association, Inc.