Meghan D Plotnick1, Katrina A D'Urzo1, Brendon J Gurd1, Kyra E Pyke2. 1. School of Kinesiology and Health Studies, Queen's University, 28 Division St., Kingston, ON, K7L 3N6, Canada. 2. School of Kinesiology and Health Studies, Queen's University, 28 Division St., Kingston, ON, K7L 3N6, Canada. pykek@queensu.ca.
Abstract
PURPOSE: To determine whether orally administered vitamin C attenuates expected mental stress-induced reductions in brachial artery endothelial function as measured by flow-mediated dilation (FMD). METHODS:Fifteen men (21 ± 2 years) were given 1000 mg of vitamin C or placebo over two visits in a randomized, double-blinded, within-subject design. Acute mental stress was induced using the Trier Social Stress Test (TSST). Saliva samples for cortisol determination and FMD measures were obtained at baseline, pre-TSST, and 30 and 90-min post-TSST. An additional saliva sample was obtained immediately post-TSST. Cardiovascular stress reactivity was characterized by changes in heart rate (HR) and mean arterial pressure (MAP). RESULTS: A significant stress response was elicited by the TSST in both conditions [MAP, HR, and salivary cortisol increased (p < 0.001)]. Overall FMD did not differ pre- vs. post-stress (time: p = 0.631) and there was no effect of vitamin C (condition: p = 0.792) (interaction between time and condition, p = 0.573). However, there was a correlation between cortisol reactivity and changes in FMD from pre- to post-stress in the placebo condition (r 2 = 0.66, p < 0.001) that was abolished in the vitamin C condition (r 2 = 0.02, p = 0.612). CONCLUSION:Acute mental stress did not impair endothelial function, and vitamin C disrupted the relationship between cortisol reactivity and changes in FMD post-stress. This suggests that acute mental stress does not universally impair endothelial function and that reactive oxygen species signaling may influence the interaction between FMD and stress responses.
RCT Entities:
PURPOSE: To determine whether orally administered vitamin C attenuates expected mental stress-induced reductions in brachial artery endothelial function as measured by flow-mediated dilation (FMD). METHODS: Fifteen men (21 ± 2 years) were given 1000 mg of vitamin C or placebo over two visits in a randomized, double-blinded, within-subject design. Acute mental stress was induced using the Trier Social Stress Test (TSST). Saliva samples for cortisol determination and FMD measures were obtained at baseline, pre-TSST, and 30 and 90-min post-TSST. An additional saliva sample was obtained immediately post-TSST. Cardiovascular stress reactivity was characterized by changes in heart rate (HR) and mean arterial pressure (MAP). RESULTS: A significant stress response was elicited by the TSST in both conditions [MAP, HR, and salivary cortisol increased (p < 0.001)]. Overall FMD did not differ pre- vs. post-stress (time: p = 0.631) and there was no effect of vitamin C (condition: p = 0.792) (interaction between time and condition, p = 0.573). However, there was a correlation between cortisol reactivity and changes in FMD from pre- to post-stress in the placebo condition (r 2 = 0.66, p < 0.001) that was abolished in the vitamin C condition (r 2 = 0.02, p = 0.612). CONCLUSION: Acute mental stress did not impair endothelial function, and vitamin C disrupted the relationship between cortisol reactivity and changes in FMD post-stress. This suggests that acute mental stress does not universally impair endothelial function and that reactive oxygen species signaling may influence the interaction between FMD and stress responses.
Entities:
Keywords:
Antioxidant; Cortisol; FMD; Flow-mediated dilation; HPA axis; ROS; Reactive oxygen species; Stress reactivity; Trier Social Stress Test
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