Rodriguez-Plaza L G, Alfieri A B, Cubeddu L X
School of Pharmacy, Central University of Venezuela, Policlinica Metropolitana, Caracas.
J Cardiovasc Risk. 1997 Oct-Dec;4(5-6):367-72.
The mechanisms by which regular exercise is associated with decreases in all-cause and cardiovascular mortality are unknown. Nitric oxide (NO) may have a role, as it is known to be an important factor in cardiovascular regulation. The relationships between physical activity and systemic formation of NO were evaluated in healthy volunteers and in patients with coronary artery disease (CAD).
Urinary excretion of NO metabolites (nitrates + nitrites) was measured in 50 men. Group 1 comprised 14 highly trained runners (90 km/week) who were tested before and after a marathon race of 42.2 km. Group 2 comprised 11 well trained men (64 km/week) who were tested before and after a 15 km race. Group 3 comprised 12 sedentary individuals who gave a single urine sample. Group 4 comprised 13 patients with CAD who were tested before and after a 6 km walk.
Group 1 showed the highest basal levels of urinary NO metabolites: 10.10 mmol/g creatinine; they were followed by group 2, with 5.60 mmol/g creatinine, group 3 with 1.59 mmol/g creatinine and patients with CAD (group 4), who had 0.35 mmol/g creatinine. After the marathon, those in group 1 showed a significant (P=0.0001) reduction of 80% in the excretion of NO metabolites. The 15 km race (group 2 and the 6 km walk (group 4), produced nonsignificant reductions in NO excretion. Patients with CAD were prospectively evaluated before and after a 12-week cardiac rehabilitation program. Their urinary excretion of NO metabolites (mmol/g creatinine) at the end of the program was 157% higher than at baseline (P=0.034). A positive, significant correlation (P=0.006) was observed between the increases in exercise capacity [in METs (one MET is equal to the body's oxygen consumption at rest, and corresponds to 3.5 ml/Kg/min)] and in NO metabolite excretion induced by the 12-week program.
The baseline urinary excretion of NO metabolites increases with increasing levels of physical activity (chronic aerobic exercise). Patients with CAD had lowest levels of urinary NO metabolites and these increased in direct proportion with the gain in functional capacity. These findings suggest that increased NO production may be a major adaptive mechanism by which chronic aerobic exercise training benefits the cardiovascular system. The marked increase in NO production induced by long-term, high levels of aerobic exercise may be protective in athletes undertaking strenuous levels of exercise.
规律运动与全因死亡率和心血管死亡率降低相关的机制尚不清楚。一氧化氮（NO）可能起作用，因为它是心血管调节中的一个重要因素。在健康志愿者和冠心病（CAD）患者中评估了体力活动与全身NO生成之间的关系。
测定了50名男性尿液中NO代谢产物（硝酸盐+亚硝酸盐）的排泄量。第1组包括14名训练有素的跑步者（每周90公里），在42.2公里的马拉松比赛前后进行了测试。第2组包括11名训练有素的男性（每周64公里），在15公里比赛前后进行了测试。第3组包括12名久坐不动的个体，他们提供了一份尿液样本。第4组包括13名CAD患者，在6公里步行前后进行了测试。
第1组尿液中NO代谢产物的基础水平最高：10.10 mmol/g肌酐；其次是第2组，为5.60 mmol/g肌酐，第3组为1.59 mmol/g肌酐，CAD患者（第4组）为0.35 mmol/g肌酐。马拉松比赛后，第1组的NO代谢产物排泄量显著降低（P=0.0001），降低了80%。15公里比赛（第2组）和6公里步行（第4组）使NO排泄量有不显著的降低。对CAD患者在12周心脏康复计划前后进行了前瞻性评估。在该计划结束时，他们尿液中NO代谢产物（mmol/g肌酐）的排泄量比基线时高157%（P=0.034）。观察到运动能力的增加[以代谢当量（METs）表示（1个MET等于身体在休息时的耗氧量，相当于3.5 ml/Kg/min）]与12周计划引起的NO代谢产物排泄增加之间存在正相关且具有显著性（P=0.006）。
NO代谢产物的基线尿液排泄量随着体力活动（慢性有氧运动）水平的增加而增加。CAD患者尿液中NO代谢产物水平最低，且这些水平与功能能力的提高成正比增加。这些发现表明，NO生成增加可能是慢性有氧运动训练有益于心血管系统的主要适应性机制。长期、高强度有氧运动引起的NO生成显著增加可能对进行高强度运动的运动员具有保护作用。
