Integrative Vascular Physiology Laboratory, Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas.
Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania.
J Appl Physiol (1985). 2021 May 1;130(5):1510-1521. doi: 10.1152/japplphysiol.00453.2020. Epub 2021 Mar 25.
Non-Hispanic black individuals suffer from an elevated prevalence of hypertension and cardiovascular disease (CVD) relative to other populations. This elevated disease risk is, in large part, related to impaired vascular function, secondary to reduced nitric oxide (NO) bioavailability. Emerging evidence suggests that dietary nitrate supplementation improves several cardiovascular parameters, including vascular function, in part by increased NO bioavailability. However, whether these findings extend to a population of black individuals is unknown. This study tested the hypothesis that forearm blood flow responses in young, non-Hispanic, black (BL) men during a mental stress challenge would be blunted relative to young, non-Hispanic, white (WH) men. We further hypothesized that acute dietary nitrate supplementation would improve this response in BL men. This study comprised two parts ( and ). investigated the difference in blood flow responses between young, BL, and WH men. In contrast, investigated the effect of acute nitrate supplementation on the responses in a subset of the BL men from . Eleven (nine for ) BL and eight WH men (23 ± 3 vs. 24 ± 4 yr, respectively) participated in this double-blind, placebo-controlled, randomized, crossover study. During each visit, hemodynamic responses during 3 min of mental stress were assessed in the brachial artery using duplex Doppler ultrasound. was completed in one visit, whereas was completed over two visits separated by ∼1 wk. During , data were collected before and 2-h postconsumption of a beverage either high in nitrate content or nitrate depleted. In , peak forearm blood flow (FBF; < 0.001), total FBF ( < 0.01), and forearm vascular conductance (FVC; < 0.001) were blunted in the BL. During , prebeverage responses were similar to and were unaffected following beverage consumption ( > 0.05 vs. prebeverage for all variables). These data indicate that young, BL men have blunted microvascular vasodilatory responses to acute mental stress, which may not be altered following acute nitrate supplementation. This study tested the hypothesis that non-Hispanic black (BL) men have a blunted forearm hyperemic response to mental stress, which would be augmented following acute nitrate supplementation. The increase in forearm blood flow during mental stress was attenuated in BL men and was not impacted by nitrate supplementation. This supports findings of altered vascular function in this population. This is especially important as BL experience a higher prevalence of stress, which contributes to CVD risk.
非西班牙裔黑人个体患高血压和心血管疾病 (CVD) 的发病率相对较高。这种疾病风险的增加在很大程度上与血管功能受损有关，这是由于一氧化氮 (NO) 生物利用度降低所致。新出现的证据表明，膳食硝酸盐补充剂可改善多种心血管参数，包括血管功能，部分原因是 NO 生物利用度增加。然而，这些发现是否适用于黑人人群尚不清楚。本研究检验了以下假设：在精神压力挑战期间，年轻的非西班牙裔黑人 (BL) 男性的前臂血流反应会比年轻的非西班牙裔白人 (WH) 男性更迟钝。我们进一步假设急性膳食硝酸盐补充会改善 BL 男性的这种反应。这项研究由两部分组成 (和)。 研究了年轻的 BL 和 WH 男性之间血流反应的差异。相比之下， 研究了急性硝酸盐补充对 中 BL 男性部分反应的影响。11 名（9 名 ，8 名 WH 男性（23 ± 3 岁与 24 ± 4 岁，分别）参加了这项双盲、安慰剂对照、随机、交叉研究。在每次就诊中，使用双功能多普勒超声在肱动脉中评估 3 分钟精神压力期间的血液动力学反应。 在一次就诊中完成，而 在两次就诊之间完成，间隔约 1 周。在 中，在饮用高硝酸盐含量或硝酸盐耗尽的饮料前后 2 小时收集数据。在 中，BL 的峰值前臂血流 (FBF; < 0.001)、总 FBF (< 0.01)和前臂血管传导率 (FVC; < 0.001)均减弱。在 中，预饮料反应与 相似，并且在饮料消耗后不受影响（与预饮料相比，所有变量均> 0.05）。这些数据表明，年轻的 BL 男性对急性精神压力的微血管舒张反应减弱，而急性硝酸盐补充不会改变这种反应。本研究检验了以下假设：非西班牙裔黑人 (BL) 男性对精神压力的前臂充血反应减弱，而急性硝酸盐补充会增强这种反应。在精神压力下，前臂血流量的增加在 BL 男性中减弱，而硝酸盐补充并没有影响。这支持了该人群血管功能改变的发现。这一点尤其重要，因为 BL 经历更高的压力患病率，这会导致 CVD 风险增加。
