Circulating brain natriuretic peptide (BNP) has recently served as a marker of left ventricular dysfunction, while treadmill exercise has been used clinically for assessing cardiac problems. The current study was undertaken to investigate the possible effect of exercise on circulating BNP concentrations. A total of 138 blood samples from 23 healthy men aged 23 to 27 years (mean, 25) was analyzed. All subjects maintained a similar diet and physical activity a week before the test. Plasma samples were drawn at baseline and immediately, 1 hour, 4 hours, 24 hours, and 48 hours after exercise. Every subject completed exercise according to the Bruce protocol with normal electrocardiogram (EKG) results. Specimens were simultaneously analyzed for concentrations of plasma BNP and other biochemical parameters including aldosterone (Aldo), adrenocorticotropic hormone (ACTH), cortisol, creatine phosphokinase (CPK), triiodothyronine (T(3)), and thyroxine (T(4)). Hematocrit (Hct), red blood cell count (RBC), and hemoglobin (Hgb) were analyzed immediately after each sampling. A transient increase in plasma BNP was found immediately after exercise (8.21 v baseline value, 3.38 pg/mL, P <.01). Twenty-two percent (5/23 subjects) had values above the normal limit (18.2 pg/mL). The Hct-corrected concentrations of plasma BNP were also significantly increased immediately after exercise compared with the baseline values (0.17 +/- 0.04 v baseline, 0.07 +/- 0.01, P <.01), but returned rapidly to baseline. Weak, but significantly positive, relationships were found between plasma BNP and T(3) and T(4). Our study demonstrates that circulating BNP values increase immediately after treadmill exercise in young adults. The elevation did not result from exercise-induced hemoconcentration. BNP concentration, however, returned to normal levels within 1 hour after exercise. Thus, we suggest that plasma samples should not be taken immediately after exercise to avoid possible artifacts.
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