Schreuder Tim H A, Green Daniel J, Hopman Maria T E, Thijssen Dick H J
Radboud Institute for Health Sciences, Radboud University Medical Center, The Netherlands.
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Western Australia, Australia.
Atherosclerosis. 2015 Jul;241(1):199-204. doi: 10.1016/j.atherosclerosis.2015.04.017. Epub 2015 Apr 18.
An inverse, dose-dependent relationship between retrograde shear rate and brachial artery endothelial function exists in young subjects. This relationship has not been investigated in older adults, who have been related to lower endothelial function, higher resting retrograde shear rate and higher risk of cardiovascular disease.
To investigate the impact of a step-wise increase in retrograde shear stress on flow-mediated dilation in older males in the upper and lower limbs.
Fifteen older (68 ± 9 years) men reported to the laboratory 3 times. We examined brachial artery flow-mediated dilation before and after 30-min exposure to cuff inflation around the forearm at 0, 30 and 60 mmHg, to manipulate retrograde shear rate. Subsequently, the 30-min intervention was repeated in the superficial femoral artery. Order of testing (vessel and intervention) was randomised.
Increases in cuff pressure resulted in dose-dependent increases in retrograde shear in both the brachial and superficial femoral artery in older subjects. In both the brachial and the superficial femoral artery, no change in endothelial function in response to increased retrograde shear was observed in older males ('time' P = 0.274, 'cufftime P = 0.791', 'cuffartery*time P = 0.774').
In contrast with young subjects, we found that acute elevation in retrograde shear rate does not impair endothelial function in older humans. This may suggest that subjects with a priori endothelial dysfunction are less responsive or requires a larger shear rate stimulus to alter endothelial function.
在年轻受试者中，逆行剪切速率与肱动脉内皮功能之间存在反比的剂量依赖性关系。在老年人中尚未对这种关系进行研究，老年人的内皮功能较低、静息逆行剪切速率较高且心血管疾病风险较高。
研究逆行剪切应力逐步增加对老年男性上下肢血流介导的血管舒张的影响。
15名老年（68±9岁）男性到实验室报到3次。我们在0、30和60mmHg压力下，对前臂进行30分钟袖带充气以控制逆行剪切速率，分别检测充气前后肱动脉血流介导的血管舒张情况。随后，在股浅动脉重复30分钟的干预。测试顺序（血管和干预）是随机的。
袖带压力增加导致老年受试者肱动脉和股浅动脉的逆行剪切呈剂量依赖性增加。在肱动脉和股浅动脉中，老年男性对逆行剪切增加的内皮功能均未观察到变化（“时间”P = 0.274，“袖带时间”P = 0.791，“袖带动脉*时间”P = 0.774）。
与年轻受试者不同，我们发现逆行剪切速率的急性升高不会损害老年人的内皮功能。这可能表明，先天存在内皮功能障碍的受试者反应性较低，或需要更大的剪切速率刺激才能改变内皮功能。
