Schreuder Tim H A, Eijsvogels Thijs M H, Greyling Arno, Draijer Richard, Hopman Maria T E, Thijssen Dick H J
a Department of Physiology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands.
Appl Physiol Nutr Metab. 2014 Feb;39(2):145-51. doi: 10.1139/apnm-2012-0450. Epub 2013 Jul 29.
Tea consumption is associated with reduced cardiovascular risk. Previous studies found that tea flavonoids work through direct effects on the vasculature, leading to dose-dependent improvements in endothelial function. Cardioprotective effects of regular tea consumption may relate to the prevention of endothelial ischaemia-reperfusion (IR) injury. Therefore, we examined the effect of black tea consumption on endothelial function and the ability of tea to prevent IR injury. In a randomized, crossover study, 20 healthy subjects underwent 7 days of tea consumption (3 cups per day) or abstinence from tea. We examined brachial artery (BA) endothelial function via flow-mediated dilation (FMD), using high resolution echo-Doppler, before and 90 min after tea or hot water consumption. Subsequently, we followed a 20-min ischaemia and 20-min reperfusion protocol of the BA after which we measured FMD to examine the potential of tea consumption to protect against IR injury. Tea consumption resulted in an immediate increase in FMD% (pre-consumption: 5.8 ± 2.5; post-consumption: 7.2 ± 3.2; p < 0.01), whilst no such change occurred after ingestion of hot water. The IR protocol resulted in a significant decrease in FMD (p < 0.005), which was also present after tea consumption (p < 0.001). This decline was accompanied by an increase in the post-IR baseline diameter. In conclusion, these data indicate that tea ingestion improves BA FMD. However, the impact of the IR protocol on FMD was not influenced by tea consumption. Therefore, the cardioprotective association of tea ingestion relates to a direct effect of tea on the endothelium in humans in vivo.
饮茶与降低心血管风险相关。先前的研究发现，茶黄酮类化合物通过对血管系统的直接作用发挥功效，从而使内皮功能呈剂量依赖性改善。经常饮茶的心脏保护作用可能与预防内皮缺血再灌注（IR）损伤有关。因此，我们研究了饮用红茶对内皮功能的影响以及茶预防IR损伤的能力。在一项随机交叉研究中，20名健康受试者进行了7天的饮茶（每天3杯）或不饮茶。我们在饮茶或饮用热水前及饮用后90分钟，使用高分辨率超声多普勒通过血流介导的血管舒张（FMD）检查肱动脉（BA）内皮功能。随后，我们对BA进行了20分钟的缺血和20分钟的再灌注方案，之后测量FMD以检查饮茶预防IR损伤的潜力。饮茶导致FMD%立即增加（饮用前：5.8±2.5；饮用后：7.2±3.2；p<0.01），而饮用热水后未发生此类变化。IR方案导致FMD显著降低（p<0.005），饮茶后也存在这种情况（p<0.001）。这种下降伴随着IR后基线直径的增加。总之，这些数据表明饮茶可改善BA的FMD。然而，IR方案对FMD的影响不受饮茶的影响。因此，饮茶的心脏保护关联与茶对人体体内内皮的直接作用有关。
