CNRS UMR - INSERM U, Angers, France.
Respir Physiol Neurobiol. 2009 Oct;169 Suppl 1:S10-2. doi: 10.1016/j.resp.2009.04.009. Epub 2009 Apr 18.
Weightlessness induces an acute syndrome called the cardiovascular deconditioning, associating orthostatic intolerance with syncope, increase in resting heart rate and decrease in physical capability. Orthostatic intolerance occurs after short term and long term head down bed rest and after long term space flight. Both head down bed rest and space flight induce a significant decrease of the spontaneous baroreflex sensitivity. However, spontaneous baroreflex sensitivity only characterizes the cardiac baroreflex loop. To go further with the analysis of cardiovascular deconditioning we were interested in the microcirculation. As the endothelium plays a crucial role in the regulation of vascular homeostasis and local blood flow, we hypothesized that endothelial dysfunction is associated with bed rest induced changes. We investigated endothelial properties before and after 56 days of bed rest in 8 women of control group and in 8 women who regularly performed physical exercise as countermeasure. Our study shows that prolonged bed rest causes impairment of endothelium-dependent functions at the microcirculation level, along with an increase in circulating endothelial cells. Endothelium should be a target for countermeasures during periods of prolonged bed rest or exposure to weightlessness.
失重会引起一种称为心血管适应性不良的急性综合征，伴有直立不耐受、晕厥、静息心率增加和身体机能下降。直立不耐受会在短期和长期头低位卧床休息以及长期太空飞行后发生。头低位卧床休息和太空飞行都会导致自主压力反射敏感性显著下降。然而，自主压力反射敏感性仅能描述心脏压力反射环。为了更深入地分析心血管适应性不良，我们对微循环感兴趣。由于内皮在血管稳态和局部血流调节中起着至关重要的作用，我们假设内皮功能障碍与卧床引起的变化有关。我们在 8 名对照组女性和 8 名定期进行体育锻炼作为对策的女性中，在卧床休息 56 天后，分别在卧床前和卧床后研究了内皮功能。我们的研究表明，长时间卧床休息会导致微循环水平的内皮依赖性功能受损，同时循环内皮细胞增加。在长时间卧床休息或暴露于失重期间，内皮应该成为对策的目标。
