Stress-induced microvascular reactivity in normal-weight and obese individuals

Obesity has been shown to have profound effects on hemodynamics and neurological states in humans. Previous studies have demonstrated that obese individuals are highly susceptible to increases in tension, anxiety, and depression. However, the relationship between mental stressors and vascular fluidity in obese humans is not well understood. Thus, the purpose of this study was to investigate mental-stress-induced microvascular reactivity (excess blood flow (EBF)) in normal-weight and obese individuals. In addition, the relationships between potential vascular response modulators (heart rate (HR) and norepinephrine (NE)) and EBF were examined. Twenty-two male subjects were classified as obese (n = 12) or normal-weight (n = 10), and each subject completed a 20 min bout of acute mental stress. Our analyses demonstrate significant elevations in forearm blood flow (FBF) and EBF immediately after mental stress in both normal-weight and obese groups. HR was only correlated with EBF immediately poststress in the normal-weight group. Furthermore, stress-induced plasma NE was not associated with FBF or EBF in either group, although in the obese group, stress-induced plasma NE was associated with body mass index and percent body fat. These results suggest that microvascular reactivity after mental stress is not directly related to plasma NE in normal-weight or obese individuals. The novel results presented in this study provide a foundation for additional examination of the mechanisms involved in the effects of mental stress on microvascular reactivity.