Previous studies showed that anabolic androgenic steroids (AAS) increase vascular resistance and blood pressure (BP) in humans. In this study, we tested the hypotheses 1) that AAS users would have increased muscle sympathetic nerve activity (MSNA) and reduced forearm blood flow (FBF) compared with AAS nonusers and 2) that there would be an association between MSNA and 24-h BP.
Twelve AAS users aged 31 ± 2 yr (means ± SE) and nine age-matched AAS nonusers aged 29 ± 2 yr participated in the study. All individuals were involved in strength training for at least 2 yr. AAS was determined by urine test (chromatography-mass spectrometry). MSNA was directly measured by microneurography technique. FBF was measured by venous occlusion plethysmography. BP monitoring consisted of measures of BP for 24 h.
MSNA was significantly higher in AAS users than that in AAS nonusers (29 ± 3 vs 20 ± 1 bursts per minute, P = 0.01). FBF (1.92 ± 0.17 vs 2.77 ± 0.24 mL·min−1·100 mL−1, P = 0.01) and forearm vascular conductance (2.01 ± 0.17 vs 2.86 ± 0.31 U, P = 0.02) were significantly lower in AAS users than that in AAS nonusers. Systolic (131 ± 4 vs 120 ± 3 mm Hg, P = 0.001), diastolic (74 ± 4 vs 68 ± 3 mm Hg, P = 0.02), and mean BP (93 ± 4 vs 86 ± 3 mm Hg, P = 0.005) and heart rate (74 ± 3 vs 68 ± 3 bpm, P = 0.02) were significantly higher in AAS users when compared with AAS nonusers. Further analysis showed that there was a significant correlation between MSNA and 24-h mean BP (r = 0.75, P = 0.002).
AAS increases MSNA and reduces muscle blood flow in young individuals. In addition, the increase in BP levels in AAS users is associated with augmented sympathetic outflow. These findings suggest that AAS increases the susceptibility for cardiovascular disease in humans.
1Heart Institute (InCor), University of São Paulo Medical School, São Paulo, BRAZIL; 2College of Pharmaceutical Sciences, Toxicology, University of São Paulo, São Paulo, BRAZIL; and 3School of Physical Education and Sport, University of São Paulo, São Paulo, BRAZIL
Address for correspondence: Carlos Eduardo Negrão, Ph.D., Instituto do Coração (InCor), Unidade de Reabilitação Cardiovascular e Fisiologia do Exercício, Av. Dr. Enéas de Carvalho Aguiar, 44, Cerqueira César, São Paulo, SP, CEP 05403-000, Brazil; E-mail: email@example.com.
Submitted for publication July 2009.
Accepted for publication September 2009.