Endothelium dependent vasodilation in young, obese adults: contribution of NOS

Endothelium dependent vasodilation (EDD) is impaired in older, obese adults. However, it remains unknown whether this impairment exists in young, obese adults. We hypothesized that young, obese adults would exhibit attenuated EDD and altered nitric oxide (NO) production. In 10 young, lean (age: 27±2 yrs; BMI: 23±1 kg/m 2 ) and 7 young, obese (23±2 yrs; 38±4 kg/m 2 ) adults forearm EDD was assessed with infusion of acetylcholine (ACH) into the brachial artery. Contribution of NO to EDD was determined by simultaneous infusion of LNMMA and ACH. Smooth muscle responses to NO were tested with nitroprusside (NTP). Forearm blood flow (FBF) was measured with Doppler ultrasound and normalized for mean arterial pressure (MAP) by calculating forearm vascular conductance (FVC =FBF/MAP). ACH infusion increased FVC (p<0.01). FVC was greater in obese versus lean adults expressed as either an absolute value (207 vs. 130 ml min −1 mmHG −1 ; p<0.01) or change from baseline (165 vs. 90; p<0.01). NOS inhibition decreased ACH mediated EDD (p=0.02) equally in lean and obese subjects. FBF responses to NTP were similar between groups. In conclusion, our data suggest that young obese adults exhibit greater EDD, but this is not due to altered NOS function. Support: NIH R01 HL105820.