Clodfelter William H, Basu Swati, Bolden Crystal, Dos Santos Patricia C, King S Bruce, Kim-Shapiro Daniel B
Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109, USA; Translational Science Center, Wake Forest University, Reynolda Campus, Winston-Salem, NC 27109, USA.
Translational Science Center, Wake Forest University, Reynolda Campus, Winston-Salem, NC 27109, USA; Department of Physics, Wake Forest University, Winston-Salem, NC 27109, USA.
Nitric Oxide. 2015 May 1;47:85-90. doi: 10.1016/j.niox.2015.04.003. Epub 2015 Apr 21.
Several studies have shown that fasting plasma nitrite (NO2(-)) is an indicator of endothelial nitric oxide synthase (NOS) activity while plasma nitrate (NO3(-)) or the sum of NO2(-) and NO3(-) (NOx) does not reflect NOS function. Plasma NO2(-) can also be elevated through dietary NO3(-) where the NO3(-) is partially reduced to NO2(-) by oral bacteria and enters the plasma through the digestive system. NO3(-) is taken up from plasma by salivary glands and the cycle repeats itself. Thus, one may propose that salivary NO2(-) is an indicator of plasma NO2(-) and consequently of NO production. Many brands of nitric oxide (NO) saliva test strips have been developed that suggest that their product is indicative of circulatory NO availability. However, data supporting a relationship between salivary and plasma NO2(-) or NO bioavailability are lacking. Here we have measured basal salivary and plasma NO2(-) and NO3(-) to determine if any correlation exists between these in 13 adult volunteers. We found no significant correlation between basal salivary and plasma NO2(-). Also no correlation exists between salivary NO3(-) and plasma NO2(-). However, we did see a correlation between salivary NO3(-) and plasma NO3(-), and between salivary NO2(-) and plasma NO3(-). In a separate study, we compared the efficiency of salivary NO3(-) reduction with the efficacy of increasing plasma NO3(-) and NO2(-) after drinking beet juice, a high NO3(-)-containing beverage, in 10 adult volunteers. No significant correlation was observed between the ex vivo salivary reduction of NO3(-) to NO2(-) and plasma increases in NO3(-) or NO2(-). These results suggest that measures of salivary NO3(-), NO2(-) or NOx are not good indicators of endothelial function. In addition, the efficiency of saliva to reduce NO3(-) to NO2(-)ex-vivo does not demonstrate one's ability to increase plasma NO2(-) following consumption of dietary NO3(-).
多项研究表明，空腹血浆亚硝酸盐（NO2(-)）是内皮型一氧化氮合酶（NOS）活性的一个指标，而血浆硝酸盐（NO3(-)）或NO2(-)与NO3(-)之和（NOx）并不能反映NOS功能。血浆NO2(-)也可通过饮食中的NO3(-)升高，其中NO3(-)被口腔细菌部分还原为NO2(-)，并通过消化系统进入血浆。NO3(-)被唾液腺从血浆中摄取，然后循环重复。因此，有人可能会提出，唾液NO2(-)是血浆NO2(-)的一个指标，因此也是NO生成的指标。已经开发出许多品牌的一氧化氮（NO）唾液测试条，表明其产品可指示循环中NO的可用性。然而，缺乏支持唾液与血浆NO2(-)或NO生物利用度之间关系的数据。在这里，我们测量了13名成年志愿者的基础唾液和血浆NO2(-)及NO3(-)，以确定它们之间是否存在任何相关性。我们发现基础唾液和血浆NO2(-)之间没有显著相关性。唾液NO3(-)与血浆NO2(-)之间也没有相关性。然而，我们确实看到了唾液NO3(-)与血浆NO3(-)之间以及唾液NO2(-)与血浆NO3(-)之间的相关性。在另一项研究中，我们比较了10名成年志愿者饮用甜菜汁（一种富含NO3(-)的饮料）后，唾液中NO3(-)还原的效率与血浆中NO3(-)和NO2(-)增加的效果。在体外，唾液中NO3(-)还原为NO2(-)与血浆中NO3(-)或NO2(-)的增加之间未观察到显著相关性。这些结果表明，唾液NO3(-)、NO2(-)或NOx的测量并非内皮功能的良好指标。此外，唾液在体外将NO3(-)还原为NO2(-)的效率并不能证明一个人在摄入饮食中的NO3(-)后增加血浆NO2(-)的能力。
