Järvisalo Mikko J, Jartti Laura, Marniemi Jukka, Rönnemaa Tapani, Viikari Jorma S A, Lehtimäki Terho, Raitakari Olli T
Department of Clinical Physiology, Turku University Central Hospital, University of Turku, Turku, Finland.
Clin Sci (Lond). 2006 Apr;110(4):475-82. doi: 10.1042/CS20050333.
Brachial artery FMD (flow-mediated dilatation) is widely used as a marker of systemic arterial endothelial function. FMD, however, shows considerable 25% day-to-day variation that hinders its clinical use. The reasons for this variability are poorly characterized. Therefore the present study was designed to clarify factors responsible for the hourly variation in endothelial function, including consuming a low-fat meal and circadian rhythms in endogenous hormonal levels. Brachial artery FMD, along with serum glucose, triacylglycerols (triglycerides) and levels of several hormones were measured six times per day on two separate days 1 week apart. On one day, the subjects (healthy males: n=12, mean age, 24 years) ate a light breakfast and a standardized lunch (23.5% fat, 48.7% carbohydrate and 27.8% protein). On the other day, they had a similar breakfast after which they fasted. Postprandial FMD values (both after breakfast and after lunch) were similar to baseline FMD. FMD showed a 28% hourly variation and 27% weekly variation. Variation in plasma levels of insulin (P=0.02) associated negatively and DHPG (3,4-dihydroxyphenylglycol) (P=0.001), a marker of sympathetic nervous activation, associated positively with variation in FMD. The effects of DHPG and insulin on FMD were independent of changes in baseline brachial artery diameter, although DHPG was also inversely associated with baseline diameter. Eating a regular low-fat meal does not have any measurable effects on brachial artery endothelial function. These data suggest that strict requirements for fasting conditions may be unnecessary when measuring peripheral endothelial function using the ultrasound technique. Circadian variation in serum insulin and sympathetic tone are physiological determinants of endothelial function.
肱动脉血流介导的舒张功能（FMD）被广泛用作全身动脉内皮功能的标志物。然而，FMD表现出相当大的每日25%的变化，这阻碍了其临床应用。这种变异性的原因目前尚不清楚。因此，本研究旨在阐明导致内皮功能每小时变化的因素，包括食用低脂餐和内源性激素水平的昼夜节律。在相隔1周的两个不同日子里，每天对肱动脉FMD以及血清葡萄糖、三酰甘油（甘油三酯）和几种激素水平进行6次测量。在其中一天，受试者（健康男性：n = 12，平均年龄24岁）吃了清淡的早餐和标准化午餐（23.5%脂肪、48.7%碳水化合物和27.8%蛋白质）。在另一天，他们吃了类似的早餐后禁食。餐后FMD值（早餐后和午餐后）与基线FMD相似。FMD显示出28%的每小时变化和27%的每周变化。胰岛素血浆水平的变化（P = 0.02）与FMD变化呈负相关，而交感神经激活标志物3,4-二羟基苯乙二醇（DHPG）（P = 0.001）与FMD变化呈正相关。尽管DHPG也与基线直径呈负相关，但DHPG和胰岛素对FMD的影响与肱动脉基线直径的变化无关。食用常规低脂餐对肱动脉内皮功能没有任何可测量的影响。这些数据表明，使用超声技术测量外周内皮功能时，可能无需严格的禁食条件。血清胰岛素和交感神经张力的昼夜变化是内皮功能的生理决定因素。
