Rassaf Tienush, Lauer Thomas, Heiss Christian, Balzer Jan, Mangold Sarah, Leyendecker Thorsten, Rottler Jessica, Drexhage Christine, Meyer Christian, Kelm Malte
Department of Medicine, Division of Cardiology, Pulmonary Diseases and Angiology, University Hospital Aachen, Pauwelsstr 30, 52074 Aachen, Germany.
Br J Sports Med. 2007 Oct;41(10):669-73; discussion 673. doi: 10.1136/bjsm.2007.035758. Epub 2007 May 11.
Nitrite is the main oxidation product of nitric oxide (NO) in plasma. It sensitively reflects changes in endothelial NO synthase (eNOS) activity under fasting conditions and serves as an endocrine NO donor, contributing to the regulation of blood flow through reaction with haemoglobin. As NO is necessary to maintain an adequate vascular response to the increased demands of blood flow, it is believed to be important for vasodilation induced by exercise.
To investigate whether the capacity of the vasculature to produce nitrite is associated with exercise performance.
With the use of chemiluminescence detection, nitrite concentrations in 55 healthy subjects (mean (SEM) age 40 (2) years; 22 men) were studied before and after an exercise test, and endothelial function was determined by measuring flow-mediated dilation of the brachial artery using high-resolution ultrasound. In a subset of subjects, the NOS inhibitor, N(G)-monomethyl-L-arginine, was applied to elucidate the effect of eNOS on changes in nitrite.
Exercise significantly (p<0.001) increased plasma nitrite from 97 (6) to 125 (8) nM. The relative increase in plasma nitrite was related to flow-mediated dilation (6.1 (0.3)%; r = 0.36; p = 0.01). N(G)-Monomethyl-L-arginine blocked increases in nitrite. Post-exercise nitrite concentration correlated with exercise performance, as determined by maximally reached stress power (r = 0.37; p<0.007), and inversely with age. Multivariate analysis showed that both age and post-exercise nitrite concentration were independent predictors of stress endurance and power.
The results suggest a role for plasma nitrite in the adaptation of haemodynamics during exercise. An impaired increase in plasma nitrite may limit exercise capacity.
亚硝酸盐是血浆中一氧化氮（NO）的主要氧化产物。它能灵敏地反映禁食条件下内皮型一氧化氮合酶（eNOS）活性的变化，并作为一种内分泌型NO供体，通过与血红蛋白反应来调节血流。由于NO对于维持血管对增加的血流需求产生充分反应是必需的，因此被认为对运动诱导的血管舒张很重要。
研究血管产生亚硝酸盐的能力是否与运动表现相关。
通过化学发光检测，对55名健康受试者（平均（标准误）年龄40（2）岁；22名男性）在运动试验前后的亚硝酸盐浓度进行了研究，并使用高分辨率超声测量肱动脉的血流介导的舒张来确定内皮功能。在一部分受试者中，应用一氧化氮合酶抑制剂N（G）-单甲基-L-精氨酸来阐明eNOS对亚硝酸盐变化的影响。
运动显著（p<0.001）使血浆亚硝酸盐浓度从97（6）纳摩尔/升增加到125（8）纳摩尔/升。血浆亚硝酸盐的相对增加与血流介导的舒张相关（6.1（0.3）%；r = 0.36；p = 0.01）。N（G）-单甲基-L-精氨酸可阻断亚硝酸盐的增加。运动后亚硝酸盐浓度与运动表现相关，通过最大应激功率来确定（r = 0.37；p<0.007），且与年龄呈负相关。多变量分析表明，年龄和运动后亚硝酸盐浓度都是应激耐力和功率的独立预测因素。
结果表明血浆亚硝酸盐在运动期间血流动力学适应中起作用。血浆亚硝酸盐增加受损可能会限制运动能力。
