Flow-mediated brachial artery vasoactivity has been proposed as a noninvasive means for assessing endothelial function. The present study is designed to assess the influence of aging on endothelial function and when vasoactivity developed initially, peaked.

We measured brachial artery diameter for 60 seconds continuously using 7.5 MHz ultrasound following 5 minutes of lower arm occlusion in 22 normal volun-teers (young group: 10 volunteers, 26.5±1.9 years; old group: 12 volunteers, 55.9±3.3 years). After sublingual administration of 0.6 mg nitroglycerine, 240 seconds continuously. And then we measure vasoactivity every 3 seconds.

Flow-mediated vasodilation (FMD) was started earlier in young group (24.3±2.8 sec; old group 28.8±3.6 sec, p=0.017). After release of occlusion, peak vasoacitivity time was at 35.5±4.7 seconds and peak vasoactivity was 8.4±1.7% in young group (old group 6.9±1.5%, p=0.099). Endothelial independent vasodilation (EID) was started at 80.7±13.3 seconds after sublingual nitroglycerine in young group (vs 80.0±19.0 sec), peaked at 177.5±16.9 seconds (vs 171.3±13.8 sec). Peak vasoactivity was higher in young group (19.1±3.1%; old group 15.9±2.5%, p=0.033).

We conclude that 1) Aging has influence on endothelial function about initiating time of vasoactivity as well as peak vaso- activity. 2) FMD can be measured around 50 seconds after release of brachial artery occlusion and EID at 180 seconds after application of sublingual nitroglycerine. 3) The initiating time of vasoactivity (under 30 seconds) can be used for evaluation of endothelial function.