[1PD4] The effect of mental stress on the flow-mediated vasodilation in young females

「Purpose」: Mental stress has been reported to be a risk factor for cardiovascular diseases such as hypertension and atherosclerosis. Because previous studies suggested that endothelial dysfunction is an important mechanism for these diseases and that estrogen has a beneficial effect on endothelium, we investigated the effect of mental stress on endothelial function during early follicular (low estrogen) and luteal (high estrogen) phases in young healthy females. 「Methods」: Ten healthy volunteers participated in this study. Brachial artery flow-mediated vasodilation (FMD) was measured before (Pre), 10 min (P-10), and 30 min (P-30) after mental arithmetic task. Arterial occlusion of forearm was conducted for each FMD test (Pre, P-10, and P-30). Mental arithmetic task was adding and subtracting 5 different digit numbers indicated by an investigator. The same protocol without mental stress was repeated on a separate day, and both protocols with and without mental stress were also repeated during follicular and luteal phases. Using high-frequency ultrasound method (Logiq 3, GE), the vessel diameter (VD) and mean flow velocity (TAmean) in the brachial artery were recorded during the mental arithmetic task and the FMD tests. Mean arterial blood pressure (MAP, Finapres), heart rate (HR, ECG recordings) were simultaneously recorded. 「Results」: The mental arithmetic stress increased HR and MAP significantly but had no effects on the VD and TAmean responses. In the FMD test, TAmean, as index of shear stress stimulus, was almost identical in all FMD tests. The peak dilation of VD (5-6 %) was observed approximately one-minute after the release of arterial occlusion. The magnitude of peak VD and the pattern of VD responses were similar before (Pre) and after mental stress (P-10 and P-30). The VD response was also similar in the experiments with and without mental stress conducted during follicular and luteal phases. 「Conclusions」: The unchanged FMD responses during Pre, P-10 and P-30 suggested that the mental arithmetic stress did not impair endothelial function in the conduit brachial artery. The estrogen level per se seemed not to modify the magnitude of FMD responses in young healthy females.