Weight loss attenuates oxidative stress related‐coronary vasoconstriction in obese adolescents

Abstract

Obesity is a risk factor for cardiovascular disease. Obesity is also a disease of oxidative stress (OS) in which cardiac output and myocardial oxygen consumption is increased. We have shown that hyperoxia (breathing 100% O2; H) can evoke coronary vasoconstriction by the oxidative quenching of NO. To examine if weight loss (WL) would alter the H related‐coronary constriction seen in obese adolescents, we measured coronary blood velocity (CBV) during H using Doppler Echocardiography before and after a 4‐week diet‐and‐exercise regimen in 6 obese male adolescents (age 15 ~ 18 yrs, BMI, 36.5±5.7 kg/m2). Three age and BMI‐matched controls were also studied. Coronary vascular resistance (CVR) was calculated as diastolic blood pressure (BP)/CBV. WL (10.1±3.1 kg) was associated with a reduction in BP, HR and rate‐pressure product (RPP) (all P<0.05). Before weight loss H increased CVR by 37±6%, whereas after WL CVR increased by only 19±6% (P<0.05) with H. CVR responses remained constant in the 3 time control subjects. Thus weight loss: 1) reduces HR, BP, and RPP; and 2) attenuates the OS related‐coronary constriction seen in obese adolescents. We speculate that: 1) the higher RPP before WL led to a higher NO production and impressive H induced constriction; 2) after WL, NO levels were reduced (less coronary flow due to lower RPP) and the effects of H were attenuated.Supported by R01 HL070222 (LS) and Tobacco Settlement Funds (LS).