Impact of acute antioxidant supplementation on vascular function and autonomic nervous system modulation in young adults with PTSD.

Posttraumatic stress disorder (PTSD) has been associated with an increase in risk of cardiovascular disease (CVD). The goal of this study was to determine if peripheral vascular dysfunction, a precursor to CVD, was present in young adults with PTSD, and if an acute antioxidant (AO) supplementation could modify this potential PTSD-induced vascular dysfunction. Thirteen individuals with PTSD were recruited for this investigation and were compared with 35 age- and sex-matched controls (CTRL). The PTSD group participated in two visits, consuming either a placebo (PTSD-PL) or antioxidants (PTSD-AO; vitamins C and E; α-lipoic acid) before their visits, whereas the CTRL subjects only participated in one visit. Upper and lower limb vascular functions were assessed via flow-mediated dilation and passive leg movement technique. Heart rate variability was utilized to assess autonomic nervous system modulation. The PTSD-PL condition, when compared with the CTRL group, reported lower arm and leg microvascular function as well as sympathetic nervous system (SNS) predominance. After acute AO supplementation, arm, but not leg, microvascular function was improved and SNS predominance was lowered to which the prior difference between PTSD group and CTRL was no longer significant. Young individuals with PTSD demonstrated lower arm and leg microvascular function as well as greater SNS predominance when compared with age- and sex-matched controls. Furthermore, this lower vascular/autonomic function was augmented by an acute AO supplementation to the level of the healthy controls, potentially implicating oxidative stress as a contributor to this blunted vascular/autonomic function.

Aerobic training and vascular protection: Insight from altered blood flow patterns.

NEW FINDING: What is the central question of this study? This study sought to determine whether prior upper limb aerobic training can attenuate the vascular dysfunction resulting from negative alteration of blood flow patterns. What is the main finding and its importance? We demonstrated that the microvasculature of young men with prior upper limb aerobic training (rowing) was equally susceptible to negatively altered blood flow patterns when compared with untrained control subjects. This finding reveals that aerobic training does not provide adequate protection against this type of vascular insult, highlighting the importance of reducing known vascular insults regardless of training status. ABSTRACT: Acute alteration of blood flow patterns can substantially reduce blood vessel function and, if consistently repeated, may chronically reduce vascular health. Aerobic exercise training is associated with improved vascular health, but it is not well understood whether aerobic training-induced vascular adaptations provide protection against acute vascular insults. This study sought to determine whether prior upper limb aerobic training can attenuate the vascular dysfunction resulting from an acute vascular insult (increased retrograde/oscillatory shear). Ten young arm-trained (AT) men (rowers; 22 ± 1 years of age) and 10 untrained (UT) male control subjects (21 ± 3 years of age) were recruited for this study. Subjects completed two brachial artery (BA) flow-mediated dilatation (FMD) tests separated by an acute bout of subdiastolic cuff inflation (SDCI) of the distal forearm. Brachial artery dilatation (normalized for the shear stimulus) and reactive hyperaemia evaluated during the BA FMD test were used to determine conduit artery and microvascular function, respectively. Data were presented as mean values ± SD. The AT group reported significantly greater whole body (peak oxygen uptake; P = 0.01) and forearm aerobic capacity (P < 0.001). The SDCI intervention significantly increased retrograde (P < 0.001) and oscillatory shear (P < 0.001) in both groups. After the SDCI, microvascular function (post-cuff release hyperaemia), but not conduit artery function (shear-induced BA dilatation), was significantly reduced from pre-SDCI values (P = 0.001) independent of group. This study revealed that young men with prior upper limb aerobic training, when compared with untrained control subjects, were equally susceptible to the microvascular dysfunction associated with an acute increase in retrograde/oscillatory shear.