Vascular Dysfunction and Posttraumatic Stress Disorder: Examining the Role of Oxidative Stress and Sympathetic Activity

Purpose: The physiological manifestations of posttraumatic stress disorder (PTSD) have been associated with an increase in risk of cardiovascular disease (CVD) independent of negative lifestyle factors. The goal of the study was to better elucidate the mechanisms behind the increased CVD risk by examining peripheral vascular function, a precursor to CVD. Moreover, this study sought to determine the role of oxidative stress and sympathetic nervous system (SNS) activity in PTSD-induced vascular dysfunction. Methods: Sixteen individuals with PTSD (10 women, 6 men; age 24 ± 4 years), and twenty-four healthy controls (CTRL; 15 women, 9 men, 24 ± 4 years), participated in the study. The PTSD group participated in two visits, consuming either a placebo or antioxidant cocktail (AO - vitamins C and E and alpha lipoic acid) prior to their visits, in a randomized order. Arm vascular function was assessed via the reactive hyperemia- induced flow mediated dilation of the brachial artery (BAFMD) technique and evaluated with Doppler ultrasonography. Brachial artery and arm microvascular function were determined by percent change of diameter from baseline normalized for BA shear rate (BAD/Shear), and blood flow area under the curve (BF AUC), respectively. Heart rate variability (HRV) was used to assess autonomic nervous system activity. Results: BF AUC was significantly lower (p = 0.02) and SNS activity was significantly higher (p = 0.02) in the PTSD group when compared to the CTRL group. BAD/Shear was not different between groups. Following the acute AO supplementation, BF AUC was augmented to which it was no longer significantly different (p = 0.16) when compared to the CTRL group. SNS activity within the PTSD group was significantly reduced (p=.007) following the AO supplementation when compared to the PL condition, and the difference between PTSD and CTRL was no longer significant (p=.41). Conclusion: Young individuals with PTSD demonstrated lower arm microvascular, but not brachial artery, function as well as higher sympathetic activity when compared to healthy controls matched for age, sex, and physical activity level. Furthermore, this microvascular dysfunction and SNS activity was attenuated by an acute AO supplementation to the level of the healthy controls. Taken together, this study revealed that the modulation of oxidative stress, via an acute AO supplementation, improved vascular dysfunction in individuals with PTSD, potentially by reducing the substantial SNS activity associated with this disorder.https://scholarscompass.vcu.edu/gradposters/1084/thumbnail.jp

Effects of Dietary Sodium Intake on Blood Flow Regulation During Exercise in Salt Resistant Individuals

PURPOSE: Dietary sodium intake guidelines is ≤2,300 mg/day, yet is exceeded by 90% of Americans. This study examined the impact of a high sodium diet on blood flow regulation during exercise. METHODS: Six males (25 ± 2 years) consumed dietary sodium intake guidelines for two weeks, with one week salt-capsule supplemented (HS: 6,900 mg/day of sodium) and the other week placebo-capsule supplemented (LS: 2,300 mg/day of sodium). At the end of each week, peripheral hemodynamic measurements [blood flow (BF), shear rate (SR), and flow mediated dilation (FMD)/SR)] of the brachial and superficial femoral artery were taken during handgrip (HG) and plantar flexion (PF) exercise, respectively. Each exercise workload was 3 minutes and progressed by 8 kilograms until exhaustion. RESULTS: There were no differences between LS and HS in blood pressure (82 ± 4 v 80 ± 5 mmHg; p = 0.3) or heart rate (56 ± 6 v 59 ± 10 bpm; p = 0.4). HG and PF exercise increased BF, SR, and FMD/SR across workload (p \u3c 0.03 for all), but no difference between diets (p \u3e 0.05 for all). CONCLUSION: Despite previous reports that HS impairs resting vascular function, this study revealed that peripheral vascular function and blood flow regulation during exercise is not impacted by a HS diet.https://scholarscompass.vcu.edu/gradposters/1082/thumbnail.jp

Limited Effects of Inorganic Nitrate Supplementation on Exercise Training Responses: A Systematic Review and Meta-analysis

Abstract Background Inorganic nitrate (NO3 −) supplementation is purported to benefit short-term exercise performance, but it is unclear whether NO3 − improves longer-term exercise training responses (such as improvements in VO2peak or time to exhaustion (TTE)) versus exercise training alone. The purpose of this systematic review and meta-analysis was to determine the effects of NO3 − supplementation combined with exercise training on VO2peak and TTE, and to identify potential factors that may impact outcomes. Methods Electronic databases (PubMed, Medscape, and Web of Science) were searched for articles published through June 2022 with article inclusion determined a priori as: (1) randomized placebo-controlled trials, (2) exercise training lasted at least three weeks, (3) treatment groups received identical exercise training, (4) treatment groups had matched VO2peak at baseline. Study quality was assessed using the Cochrane Risk-of-Bias 2 tool. Standardized mean difference (SMD) with 95% confidence intervals (CI) were calculated using restricted maximum likelihood estimation between pre- and post-training differences in outcomes. Moderator subgroup and meta-regression analyses were completed to determine whether the overall effect was influenced by age, sex, NO3 − dosage, baseline VO2peak, health status, NO3 − administration route, and training conditions. Results Nine studies consisting of eleven trials were included: n = 228 (72 females); age = 37.7 ± 21 years; VO2peak: 40 ± 18 ml/kg/min. NO3 − supplementation did not enhance exercise training with respect to VO2peak (SMD: 0.18; 95% CI: -0.09, 0.44; p = 0.19) or TTE (SMD: 0.08; 95% CI: − 0.21, 0.37; p = 0.58). No significant moderators were revealed on either outcome. Subset analysis on healthy participants who consumed beetroot juice (BRJ) revealed stronger trends for NO3 − improving VO2peak (p = 0.08) compared with TTE (p = 0.19), with no significant moderators. Sunset funnel plot revealed low statistical power in all trials. Conclusions NO3 − supplementation combined with exercise training may not enhance exercise outcomes such as VO2peak or TTE. A trend for greater improvement in VO2peak in healthy participants supplemented with BRJ may exist (p = 0.08). Overall, future studies in this area need increased sample sizes, more unified methodologies, longer training interventions, and examination of sex as a biological variable to strengthen conclusions