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目的研究15 d-6°头低位卧床(HDBR)对女性立位耐力的影响。方法 15名女性青年志愿者经历15 d-6°HDBR,于卧床前1天及卧床后第1天分别接受70°被动立位测试,记录测试全程的心血管血液动力学指标,同时观察血浆肾素活性(PRA)、血管紧张素Ⅱ(ATⅡ)和去甲肾上腺素(NE)含量变化。结果经过15 d头低位卧床后,女性立位耐力不良的发生率为8/15(53.3%)。其中,晕厥前症状中止者为6/15(40.0%),立位后心动过速(POTS)中止者为2/15(13.3%)。立位刺激可引起舒张压、心率和血管总外周阻力明显增加(P<0.05),每博量和心输出量显著降低(P<0.05)。同时,15 d HDBR可显著增加安静平卧位时的舒张压和心率,并减少每博量,但对血管总外周阻力和心输出量的影响并不明显(P>0.05)。立位耐力正常和不良者的差异主要表现为心率(HR)在立位刺激后有明显的增加,组间差异明显。血液生化指标结果显示两组间NE基础水平有显著差异,但在立位刺激下的NE含量的变化幅度未有明显差别(P>0.05)。立位刺激可导致血浆中ATⅡ含量的明显升高,而15 d HDBR则可导致血浆PRA的明显减少(P<0.01)。结论经过15 d头低位卧床后,女性立位耐力不良发生率较高,且存在着不同的表现类型。
Objective To study the effect of 15 d-6 ° head-down bed (HDBR) on female standing endurance. Methods Fifteen young female volunteers underwent 15 d-6 ° HDBR, and received 70 ° passive stand test one day before bedtime and the first day after bed rest. Cardiovascular hemodynamics indices were recorded during the test. (PRA), angiotensin Ⅱ (AT Ⅱ) and norepinephrine (NE) content changes. Results After 15 days of low bed rest, the incidence of poor standing in female standing was 8/15 (53.3%). Among them, 6/15 (40.0%) were stopped before symptoms of syncope, and 2/15 (13.3%) were stopped after orthostatic tachycardia (POTS). Orthostatic stimulation can cause diastolic blood pressure, heart rate and total peripheral vascular resistance increased significantly (P <0.05), and each volume and cardiac output significantly reduced (P <0.05). At the same time, 15d HDBR significantly increased the diastolic blood pressure and heart rate in quiet supine position and decreased the volume of each volume, but had no significant effect on the total peripheral resistance and cardiac output (P> 0.05). The main difference between standing and normal endurance was poor heart rate (HR) increased significantly after standing position stimulation, significant differences between groups. The biochemical indexes of blood showed significant differences in NE basal levels between the two groups, but there was no significant difference in NE content between the two groups (P> 0.05). The upright stimulation can lead to a significant increase in plasma AT II levels, while 15 d HDBR can lead to a significant reduction in plasma PRA (P <0.01). Conclusions After 15 days of low bed rest, the incidence of end-stage stamina in women is high, and there are different manifestations.