PDF(Pubmed)
Abstract：
As part of our investigations of intraocular pressure (IOP) as a potential contributing factor to the spaceflight-associated neuro-ocular syndrome using the 6° head-down tilt (6°HDT) bed rest experimental model, we compared the effect of rest and isometric exercise in prone and supine 6°HDT positions on IOP with that observed in the seated position.
Ten male volunteers (age = 22.5 ± 3.1 yrs) participated in six interventions. All trials comprised a 10-min rest period, a 3-min isometric handgrip exercise at 30% of participant\'s maximum, and a 10-min recovery period. The trials were conducted under normocapnic (NCAP) or hypercapnic (FI CO2 = 0.01; HCAP) conditions, the latter mimicking the ambient conditions on the International Space Station. IOP, systolic and diastolic pressures, and heart rate (HR) were measured during the trials.
Isometric exercise-induced elevations in HR and mean arterial blood pressure. IOP in the prone 6°HDT position was significantly higher (p < 0.001) compared to IOP in supine 6°HDT position and seated trials at all time points. IOP increased with exercise only in a seated HCAP trial (p = 0.042). No difference was observed between trials in NCAP and HCAP. IOP in the prone 6°HDT position was constantly elevated above 21 mmHg, the lower limit for clinical ocular hypertension.
IOP in the prone 6°HDT position was similar to IOP reported in astronauts upon entering microgravity, potentially indicating that prone, rather than supine 6°HDT position might be a more suitable experimental analog for investigating the acute ocular changes that occur in microgravity.
Ten male volunteers (age = 22.5 ± 3.1 yrs) participated in six interventions. All trials comprised a 10-min rest period, a 3-min isometric handgrip exercise at 30% of participant\'s maximum, and a 10-min recovery period. The trials were conducted under normocapnic (NCAP) or hypercapnic (FI CO2 = 0.01; HCAP) conditions, the latter mimicking the ambient conditions on the International Space Station. IOP, systolic and diastolic pressures, and heart rate (HR) were measured during the trials.
Isometric exercise-induced elevations in HR and mean arterial blood pressure. IOP in the prone 6°HDT position was significantly higher (p < 0.001) compared to IOP in supine 6°HDT position and seated trials at all time points. IOP increased with exercise only in a seated HCAP trial (p = 0.042). No difference was observed between trials in NCAP and HCAP. IOP in the prone 6°HDT position was constantly elevated above 21 mmHg, the lower limit for clinical ocular hypertension.
IOP in the prone 6°HDT position was similar to IOP reported in astronauts upon entering microgravity, potentially indicating that prone, rather than supine 6°HDT position might be a more suitable experimental analog for investigating the acute ocular changes that occur in microgravity.
摘要：
作为我们研究的一部分，眼内压（IOP）是使用6°头向下倾斜（6°HDT）卧床实验模型的航天相关神经眼综合征的潜在促成因素，我们比较了俯卧和仰卧6°HDT位置的休息和等距运动对IOP的影响与坐位的影响。
10名男性志愿者（年龄=22.5±3.1岁）参加了6次干预。所有试验都包括10分钟的休息期，3分钟的等距手握练习，参与者最大值的30%，和10分钟的恢复期。试验在正常二氧化碳(NCAP)或高二氧化碳(FICO2=0.01;HCAP)条件下进行，后者模仿国际空间站的环境条件。IOP,收缩压和舒张压,在试验期间测量心率(HR)。
等轴运动引起的HR和平均动脉血压升高。在所有时间点,俯卧6°HDT位置的IOP显著高于仰卧6°HDT位置和坐姿试验的IOP(p<0.001)。仅在坐位HCAP试验中，IOP随运动而增加（p=0.042）。在NCAP和HCAP的试验之间没有观察到差异。俯卧6°HDT位置的IOP不断升高至21mmHg以上，临床高眼压的下限。
俯卧6°HDT位置的IOP与宇航员在进入微重力时报道的IOP相似，可能表明这种倾向，而不是仰卧6°HDT位置可能是更适合研究微重力下急性眼部变化的实验类似物。
10名男性志愿者（年龄=22.5±3.1岁）参加了6次干预。所有试验都包括10分钟的休息期，3分钟的等距手握练习，参与者最大值的30%，和10分钟的恢复期。试验在正常二氧化碳(NCAP)或高二氧化碳(FICO2=0.01;HCAP)条件下进行，后者模仿国际空间站的环境条件。IOP,收缩压和舒张压,在试验期间测量心率(HR)。
等轴运动引起的HR和平均动脉血压升高。在所有时间点,俯卧6°HDT位置的IOP显著高于仰卧6°HDT位置和坐姿试验的IOP(p<0.001)。仅在坐位HCAP试验中，IOP随运动而增加（p=0.042）。在NCAP和HCAP的试验之间没有观察到差异。俯卧6°HDT位置的IOP不断升高至21mmHg以上，临床高眼压的下限。
俯卧6°HDT位置的IOP与宇航员在进入微重力时报道的IOP相似，可能表明这种倾向，而不是仰卧6°HDT位置可能是更适合研究微重力下急性眼部变化的实验类似物。
