Nitric oxide seems to be involved in the altitude acclimatization process due to its ability to regulate pulmonary, cardiovascular and muscular responses to hypoxia. In this study, we investigated the plasma nitrate (NO₃^-) and nitrite (NO₂^-) response to hypobaric hypoxia in two groups of lowlanders exposed at different altitudes.

For seven days, fourteen subjects were evaluated at Casati Hut (3269 m a.s.l. M.CEVEDALE) and eleven individuals were studied at Capanna Regina Margherita (4554 m a.s.l. M.ROSA). Before expeditions and at different time points during high-altitude sojourn, plasma NO₃^- and NO₂^- concentrations were measured by chemiluminescence. Resting peripheral arterial oxygen saturation (SpO₂), heart rate (HR) and mean arterial blood pressure (MAP) were monitored during the experimental period. Possible confounding factors such as dietary NO₃^- intake, physical activity and altitude changes were controlled.

Sea level plasma NO₃^- and NO₂^- concentrations significantly increased at altitude in both M.CEVEDALE group (+26.2 μM, p≤0.0001, 95% CI [+17.6, +34.8] and +559.2 nM, p≤0.0001, [+332.8, +785.6]) and M.ROSA group (+18.7 μM, p≤0.0001, [+10.8, +26.5] and +463.7 nM, p≤0.0001, [+314.3, +613.0]). Average peak value in NO metabolites concentration occurred earlier in M.CEVEDALE group vs M.ROSA group (NO₃^-, day 3 vs day 5, p=0.007; NO₂^-, day 3 vs day 5, p=0.019). In both groups, resting SpO₂, HR and MAP values changed according to altitude levels.

This study shows that exposure to hypobaric hypoxia affects nitric oxide metabolites, resulting in a significant increase in plasma NO₃^- and NO₂^- concentrations from sea level values. Interestingly, the higher the altitude reached, the longer the time taken to reach a peak in plasma concentrations of nitric oxide metabolites.

一氧化氮似乎能够参与海拔高度适应过程，因为它具有调节肺，心血管和肌肉对缺氧反应的能力。在这项研究中，我们调查了等离子体硝酸盐（NO ₃ ^- ）和亚硝酸根（NO ₂ ^- ），以低压缺氧反应在两组不同海拔暴露平地的。

在7天的时间里，在Casati Hut（M.CEVEDALE，3269 m）对14位受试者进行了评估，在Capanna Regina Margherita（对M.ROSA，4554 m）中，对11个人进行了研究。高空逗留期间考察和在不同时间点之前，等离子体NO ₃ ^-和NO ₂ ^-浓度是通过测量化学发光。在实验期间监测静止的外周动脉血氧饱和度（SpO ₂），心率（HR）和平均动脉血压（MAP）。可能的混杂因素如饮食NO ₃ ^-摄取，体力活动和海拔高度变化来控制。

海平面等离子体NO ₃ ^-和NO ₂ ^-浓度显著在高海拔地区既M.CEVEDALE组（26.2μM，在增加p ≤0.0001，95％CI [17.6，34.8]和559.2纳米，p ≤0.0001，[ 332.8，785.6]）和M.ROSA组（18.7μM，p ≤0.0001，[10.8，26.5]和463.7纳米，p ≤0.0001，[314.3，613.0]）。在NO的代谢产物浓度平均峰值前面M.CEVEDALE组发生VS M.ROSA基（NO ₃ ^- ，第3天VS第5天，p = 0.007; NO ₂ ^- ，第3天VS第5天，p= 0.019）。在两组中，静息SpO ₂，HR和MAP值均根据海拔水平而变化。

这项研究表明，暴露于低压缺氧影响一氧化氮代谢物，导致血浆NO一个显著增加₃ ^-和NO ₂ ^-从海平面值浓度。有趣的是，到达的海拔越高，一氧化氮代谢产物的血浆浓度达到峰值所需的时间就越长。