Reduced cardiovagal baroreflex gain in visceral obesity: implications for the metabolic syndrome

The influence of excess total and abdominal adiposity on cardiovagal baroreflex gain remains unclear. We tested the hypotheses that cardiovagal baroreflex gain would be reduced in men with 1) higher [higher fat (HF), mass >20 kg, n = 11] compared with lower [lower fat (LF), mass <20 kg, n = 10] levels of total body and abdominal fat and 2) higher abdominal visceral fat (HAVF; n = 10) compared with total body weight- and subcutaneous fat-matched peers with lower abdominal visceral fat (LAVF; n = 7) levels. To accomplish this, we measured cardiovagal baroreflex gain (modified Oxford technique), body composition (dual energy X-ray absorptiometry), and abdominal visceral and subcutaneous fat (computed tomography) in sedentary men (age, 18-40 yr; body mass index, <34.9 kg/m(2)) across a wide range of adiposity. Cardiovagal baroreflex gain was significantly lower in HF compared with LF (14.3 +/- 2.8 vs. 21.4 +/- 2.8 ms/mmHg, respectively). In addition, cardiovagal baroreflex gain was lower in HAVF compared with LAVF (13.0 +/- 2.0 vs. 21.4 +/- 3.6 ms/mmHg, P < 0.05). Therefore, the results of the present study indicate that cardiovagal baroreflex gain is reduced in men with elevated total body and abdominal fat mass. The reduced cardiovagal baroreflex gain in these individuals appears to be linked to their higher level of abdominal visceral fat. Importantly, reduced cardiovagal baroreflex gain may contribute to the increased risk of cardiovascular disease observed in men with the metabolic syndrome.