School of Health Professions, Faculty of Health & Human Sciences, University of Plymouth, UK.
School of Health Professions, Faculty of Health & Human Sciences, University of Plymouth, UK; Institute of Health & Community, University of Plymouth, UK.
Nitric Oxide. 2019 Jun 1;87:43-51. doi: 10.1016/j.niox.2019.03.001. Epub 2019 Mar 7.
Interest in inorganic nitrate and nitrite has grown substantially over the past decade as research has revealed the role of these anions in enhancing nitric oxide (NO) availability through an oral pathway. Nitrite synthesis in the mouth seems to be an important mechanism to feed the circulatory system with this anion. This is interesting since greater plasma nitrite concentration has been associated with better fitness levels in humans, but this question has not been investigated in relation to salivary nitrite concentration. Additionally, no previous study has investigated the oral nitrate-reducing capacity in regards to peak oxygen uptake (VO) or peak power output (W) in humans. Thus, the main goal of this study was to investigate whether salivary nitrite and nitrate concentration and the oral nitrate-reducing capacity were associated with VO2 and W in healthy humans. Fifty individuals (22 females and 28 males; 38.8 ± 14.3 years/old; BMI = 22.8 ± 3.9) performed a graded exercise test on a cycle ergometer to assess their VO and W. Unstimulated salivary samples were taken before and 20 min after exercise to measure nitrate/nitrite, pH and lactate. The oral nitrate-reducing capacity was also assessed in 25 subjects before and after exercise. Oral nitrate-reducing capacity was positively associated with W (r = 0.64; P = 0.001) and the VO (r = 0.54; P = 0.005). Similar correlations were found when these variables were analysed after exercise. In addition, a significant decrease in salivary pH (pre: 7.28 ± 0.361; post-exercise: 7.16 ± 0.33; P = 0.003) accompanied by an increase of salivary lactate (pre: 0.17 ± 0.14 mmol/L; post-exercise: 0.48 ± 0.38; P < 0.001) was found after exercise. However, these changes did not have any impact on salivary nitrate/nitrite concentration and the oral nitrate-reducing capacity after exercise. In conclusion, this is the first evidence showing a link between the oral nitrate-reducing capacity and markers of aerobic fitness levels in healthy humans.
过去十年中，人们对无机硝酸盐和亚硝酸盐的兴趣大幅增加，因为研究表明这些阴离子通过口服途径增强一氧化氮 (NO) 的可用性发挥着作用。口腔中亚硝酸盐的合成似乎是为循环系统提供这种阴离子的重要机制。这很有趣，因为人类血浆中亚硝酸盐浓度越高，适应能力水平就越好，但这个问题还没有针对唾液中亚硝酸盐浓度进行研究。此外，以前没有研究调查过口腔硝酸盐还原能力与人类最大摄氧量 (VO) 或最大功率输出 (W) 的关系。因此，本研究的主要目的是调查健康人群的唾液亚硝酸盐和硝酸盐浓度以及口腔硝酸盐还原能力是否与 VO 和 W 相关。50 名个体（22 名女性和 28 名男性；38.8±14.3 岁/岁；BMI=22.8±3.9）在自行车测功计上进行了分级运动测试，以评估他们的 VO 和 W。在运动前和运动后 20 分钟，采集未刺激的唾液样本以测量硝酸盐/亚硝酸盐、pH 值和乳酸。还在 25 名受试者中在运动前后评估了口腔硝酸盐还原能力。口腔硝酸盐还原能力与 W（r=0.64；P=0.001）和 VO（r=0.54；P=0.005）呈正相关。在运动后分析这些变量时也发现了类似的相关性。此外，运动后唾液 pH 值（运动前：7.28±0.361；运动后：7.16±0.33；P=0.003）显著降低，同时唾液乳酸水平升高（运动前：0.17±0.14 mmol/L；运动后：0.48±0.38 mmol/L；P<0.001）。然而，这些变化对运动后唾液硝酸盐/亚硝酸盐浓度和口腔硝酸盐还原能力没有任何影响。总之，这是首次在健康人群中证明口腔硝酸盐还原能力与有氧适应水平的标志物之间存在关联的证据。
