Demiot Claire, Dignat-George Françoise, Fortrat Jacques-Olivier, Sabatier Florence, Gharib Claude, Larina Irina, Gauquelin-Koch Guillemette, Hughson Richard, Custaud Marc-Antoine
CHU d'Angers, Centre de Recherche Clinique, Angers, France.
Am J Physiol Heart Circ Physiol. 2007 Nov;293(5):H3159-64. doi: 10.1152/ajpheart.00591.2007. Epub 2007 Aug 31.
Sedentary behavior has deleterious effects on the cardiovascular system, including reduced endothelial functions. A 2-mo bed rest study in healthy women [women international space simulation for exploration (WISE) 2005 program] presented a unique opportunity to analyze the specific effects of prolonged inactivity without other vascular risk factors on the endothelium. We investigated endothelial properties before and after 56 days of bed rest in 8 subjects who performed no exercise (control group: No-EX) and in 8 subjects who regularly performed treadmill exercise in a lower body negative pressure chamber as well as resistance exercise (countermeasure group, EX). A functional evaluation of the microcirculation in the skin was assessed with laser Doppler. We studied endothelium-dependent and -independent vasodilation using iontophoresis of acetylcholine and sodium nitroprusside, respectively. We also measured circulating endothelial cells (CECs), an index of endothelial damage. In the No-EX group, endothelium-dependent vasodilation was significantly reduced (35.4 +/- 4.8% vs. 24.1 +/- 3.8%, P < 0.05) by bed rest with a significant increase in the number of CECs (3.6 +/- 1.4 vs. 10.6 +/- 2.7 ml(-1), P < 0.05). In the EX group, endothelium-dependent vasodilation and number of CECs were preserved. Our study shows that in humans prolonged bed rest causes impairment of endothelium-dependent function at the microcirculatory level, along with an increase in circulating endothelial cells. Microcirculatory endothelial dysfunction might participate in cardiovascular deconditioning, as well as in several bed rest-induced pathologies. We therefore conclude that the endothelium should be a target for countermeasures during periods of prolonged deconditioning.
久坐行为对心血管系统有有害影响，包括内皮功能降低。一项针对健康女性的为期2个月的卧床休息研究（2005年女性国际太空探索模拟计划）提供了一个独特的机会，来分析在没有其他血管危险因素的情况下长期不活动对内皮的具体影响。我们调查了8名不进行运动的受试者（对照组：无运动组）和8名定期在下肢负压舱进行跑步机运动以及抗阻运动的受试者（对策组，运动组）在卧床休息56天前后的内皮特性。用激光多普勒评估皮肤微循环的功能。我们分别使用乙酰胆碱和硝普钠离子导入法研究内皮依赖性和非依赖性血管舒张。我们还测量了循环内皮细胞（CEC），这是内皮损伤的一个指标。在无运动组中，卧床休息使内皮依赖性血管舒张显著降低（35.4±4.8%对24.1±3.8%，P<0.05），同时循环内皮细胞数量显著增加（3.6±1.4对10.6±2.7 ml-1，P<0.05）。在运动组中，内皮依赖性血管舒张和循环内皮细胞数量得以保留。我们的研究表明，在人类中，长期卧床休息会导致微循环水平内皮依赖性功能受损，同时循环内皮细胞增加。微循环内皮功能障碍可能参与心血管失健，以及几种卧床休息引起的病症。因此，我们得出结论，在内皮长期失健期间，内皮应成为对策的目标。
