Penn State Hershey Heart and Vascular Institute, The Milton S. Hershey Medical Center, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Eur J Appl Physiol. 2013 Feb;113(2):519-28. doi: 10.1007/s00421-012-2459-9. Epub 2012 Jul 20.
Obesity is a disease of oxidative stress (OS). Acute hyperoxia (breathing 100 % O(2)) can evoke coronary vasoconstriction by the oxidative quenching of nitric oxide (NO). To examine if weight loss would alter the hyperoxia-related coronary constriction seen in obese adolescents, we measured the coronary blood flow velocity (CBV) response to hyperoxia using transthoracic Doppler echocardiography before and after a 4-week diet and exercise regimen in 6 obese male adolescents (age 13-17 years, BMI 36.5 ± 2.3 kg/m(2)). Six controls of similar age and BMI were also studied. The intervention group lost 9 ± 1 % body weight, which was associated with a reduced resting heart rate (HR), reduced diastolic blood pressure (BP), and reduced RPP (all P < 0.05). Before weight loss, hyperoxia reduced CBV by 33 ± 3 %. After weight loss, CBV only fell by 15 ± 3 % (P < 0.05). In the control group, CBV responses to hyperoxia were unchanged during the two trials. Thus weight loss: (1) reduces HR, BP, and RPP; and (2) attenuates the OS-related coronary constrictor response seen in obese adolescents. We postulate that: (1) the high RPP before weight loss led to higher myocardial O(2) consumption, higher coronary flow and greater NO production, and in turn a large constrictor response to hyperoxia; and (2) weight loss decreased myocardial oxygen demand and NO levels. Under these circumstances, hyperoxia-induced vasoconstriction was attenuated.
肥胖是一种氧化应激（OS）疾病。急性高氧（呼吸 100% 的 O(2)）可通过氧化猝灭一氧化氮（NO）引起冠状动脉收缩。为了研究减肥是否会改变肥胖青少年中与高氧相关的冠状动脉收缩，我们使用经胸多普勒超声心动图在 6 名肥胖男性青少年（年龄 13-17 岁，BMI 36.5 ± 2.3 kg/m(2))进行为期 4 周的饮食和运动方案前后测量了冠状动脉血流速度（CBV）对高氧的反应。还研究了 6 名年龄和 BMI 相似的对照组。干预组体重减轻了 9 ± 1%，这与静息心率（HR）降低、舒张压（BP）降低和 RPP 降低（均 P < 0.05）有关。减肥前，高氧使 CBV 降低了 33 ± 3%。减肥后，CBV 仅下降 15 ± 3%（P < 0.05）。在对照组中，两次试验中 CBV 对高氧的反应均无变化。因此，减肥：(1) 降低 HR、BP 和 RPP；(2) 减轻肥胖青少年中与 OS 相关的冠状动脉收缩反应。我们推测：(1) 减肥前高 RPP 导致心肌 O(2)消耗增加、冠状动脉流量增加和 NO 产生增加，进而对高氧产生较大的收缩反应；(2) 减肥降低了心肌需氧量和 NO 水平。在这种情况下，高氧诱导的血管收缩得到了减轻。
