间断头高位与站立位可对抗模拟失重大鼠股动脉收缩反应性的降低

目的 观察和比较头高位（HUT）与站立位（STD）对模拟失重所致股动脉收缩反应性降低的影响及其时间依赖性。方法 49只雄笥SD大鼠随机分为对照组、模拟失重组、头高位2h组、头高位4h组、站立位1h组、站立位2h组和站立位4h组，每组7只。利用离体股动脉血管环技术测定7组大鼠股动脉对血管收缩剂的反应。结果 悬吊大鼠股动脉血管环对KCl和苯肾上腺素的收缩反应性显降低，头高位与站立位组大鼠的股动脉血管环对KCl和苯肾上腺素收缩反应均较悬吊组显增强，与同步对照组相比已无显差异。结论 4wk模拟失重可以使大鼠股动脉的收缩反应性降低，而头高位与站立位均可对抗大鼠股动脉的收缩反应性的降低，这些结果提示间断性人工重力可对抗失重对血管所产生的影响。     

太空发育鸡胚的前庭感受器细胞形态学研究

为了探讨太空微重力对鸡胚前庭感觉上皮细胞的形态发育的影响 ,选取在航天飞机 (STS-2 9)发育鸡胚和地面发育鸡胚各两只 ,利用计算机显微测量技术分别测量椭圆囊和球囊的毛细胞、支持细胞核的切面面积、周长、形状系数。太空发育鸡胚的球囊支持细胞核的切面面积、周长显著大于地面组 ,形状系数无差异 ;太空发育鸡胚的椭圆囊支持细胞核的切面面积、周长、形状系数以及椭圆囊和球囊毛细胞的切面面积、周长与地面发育鸡胚相比无明显差异。微重力可能对球囊支持细胞核的体积发育有影响 ,对椭圆囊和球囊的毛细胞以及椭圆囊支持细胞核的形态发育无影响。     

尾部悬吊大鼠胸主动脉、肺动脉超微结构变化的动态观察

目的观察模拟微重力时大小循环动脉血管超微结构重塑随时间变化的差异,为微重力后立位耐力降低的机制研究积累资料。方法用透射电镜观察-30°尾部悬吊7d(TS7组)、14d(TS14组)及对照组大鼠胸主动脉、肺动脉壁超微结构的变化。结果TS7组胸主动脉内皮细胞表面出现绒毛状突起,部分线粒体空泡变性,内皮下基膜有分层,内弹力板较厚,且厚度不均匀,内弹力板下出现大量的胶原纤维;TS14组胸主动脉内皮细胞变性较明显,部分内皮细胞基质致密化,基膜复层化,内弹力板有破碎,弹力纤维增多。TS7组肺动脉部分内皮细胞突起,细胞内出现脂滴,内皮细胞基膜出现分层状改变,弹力板变薄、断裂,其下方可见收缩型平滑肌及合成型平滑肌细胞;TS14组肺动脉内皮细胞空泡变性较明显,内弹力板未见明显改变,弹力板内外均可见较多的胶原纤维和弹力纤维,内弹力板下方以收缩型平滑肌为主。结论TS7组大鼠胸主动脉和肺动脉出现损伤和增殖并存,以肺动脉较明显;TS14组肺动脉趋于形成新的稳定结构,而胸主动脉新稳定结构还未形成。模拟微重力时大小循环血管发生了结构重塑,大小循环血管重塑的时间过程不同归因于模拟微重力初期由下体转移而来的体液进入大小循环高峰期的时间差。     

Effects of 84‐days of bedrest and resistance training on single muscle fibre myosin heavy chain distribution in human vastus lateralis and soleus muscles

Aim: This investigation determined the effects of 84 days of bedrest on the composition of myosin heavy chain (MHC) in single skeletal muscle fibres with and without a resistance‐training countermeasure programme. Methods: Muscle biopsies were obtained from the m. vastus lateralis (VL) and m. soleus (SOL) before and after 84 days of bedrest. While control (BR) subjects (VL n = 9; SOL n = 3) refrained from exercise, BRE subjects (VL n = 8; SOL n = 3) performed knee extensor and plantar flexor resistance exercise every third day. Approximately 110 fibres per sample were analysed for MHC composition using SDS‐PAGE. Results: BR–VL had 16 and 14% decreases (P < 0.05) in MHC I and IIa fibres, respectively. There were 10% increases (P < 0.05) in MHC I/IIa, IIa/IIx, I/IIa/IIx, and a ～30% increase (P < 0.05) in total hybrid fibres. BRE‐VL showed a 15% reduction (P < 0.05) in MHC I fibres, no change in MHC IIa fibres, and a 13% increase (P < 0.05) in total hybrids. BR–SOL had a 19% decrease (P < 0.05) in MHC I fibres with a 22% increase in total hybrids. BRE–SOL showed no change in MHC composition across all fibre types. Conclusion: These data suggest that the exercise countermeasures programme prevented MHC shifts in the SOL and mitigated MHC shifts in the VL. Furthermore, in the VL it appears that the resistance training programme employed in this investigation during bedrest, emphasized the use of MHC IIa phenotype muscle fibres.     

Calbindins decreased after space flight

Exposure of the body to microgravity during space flight causes a series of well-documented changes in Ca²⁺ metabolism, yet the cellular and molecular mechanisms leading to these changes are poorly understood. Calbindins, vitamin D-dependent Ca²⁺ binding proteins, are believed to have a significant role in maintaining cellular Ca²⁺ homeostasis. In this study, we used biochemical and immunocytochemical approaches to analyze the expression of calbinding-D_28k and calbindin-D_9k in kidneys, small intestine, and pancreas of rats flown for 9 d aboard the space shuttle. The effects of microgravity on calbindins in rats from space were compared with synchronous Animal Enclosure Module controls, modeled weightlessness animals (tail suspension), and their controls. Exposure to microgravity resulted in a significant and sustained decrease in calbindin-D_28k content in the kidney and calbinding-D_9k in the small intestine of flight animals, as measured by enzyme-linked immunosorbent assay (ELISA). Modeled weightlessness animals exhibited a similar decrease in calbindins by ELISA. Immunocytochemistry (ICC) in combination with quantitative computer image analysis was used to measurein situ the expression of calbindins in the kidney and the small intestine, and the expression of insulin in pancreas. There was a large decrease of immunoreactivity in renal distal tubular cell-associated calbindin-D_28k and in intestinal absorptive cell-associated calbindin-D_9k of space flight and modeled weightlessness animals compared with matched controls. No consistent difference in pancreatic insulin immunoreactivity between space flight, modeled weightlessness, and controls was observed. Regression analysis of results obtained by quantitative ICC and ELISA for space flight, modeled weightlessness animals, and their controls demonstrated a significant correlation. These findings after a short-term exposure to microgravity or modeled weightlessness suggest that a decreased expression of calbindins may contribute to the disorders of Ca²⁺ metabolism induced by space flight.     

Variations in Digestive Physiology of Rats After Short Duration Flights Aboard the US Space Shuttle

The purpose of this work was to assess the influence of microgravity on several endogenous and microbial parameters of digestive physiology. On the occasion of two Spacelab Life Sciences missions, SLS-1 (a 9-day space flight) and SLS-2 (a 14-day space flight), Sprague-Dawley rats flown aboard the US space shuttle were compared to age-matched ground-based controls. In both flights, exposure to microgravity modified cecal fermentation: concentration and profile of short-chain fatty acids were altered, whereas urea and ammonia remained unchanged. Only in SLS-1 was there an induction of intestinal glutathione-S-transferase. Additional analyses in SLS-2 showed a decrease of hepatic CYP450 and of colonic goblet cells containing neutral mucin. After a postflight recovery period equal to the mission length, only modifications of the hepatic and intestinal xenobiotic metabolizing enzymes still persisted. These findings should help to predict the alterations of digestive physiology and detoxification potential likely to occur in astronauts. Their possible influence on health is discussed.     

影响植物栽培的空问飞行因素

植物栽培是空间站和空间生保系统的重要研究课题,因其不仅可以参与水气循环维持系统的稳定,而且可以为航天员提供新鲜蔬菜,供应多种维生素和微量元素,并有一定的抗辐射和抗氧化作用,对航天员的生理和心理健康都有积极意义.进行空间植物栽培必须要考虑到空间飞行因素对植物生长发育的影响.空间飞行因素主要可分为三类:外部因素(宇宙辐射、真空、温度),动态(微重力、加速度、振动、噪声)和飞船内部因素(密闭隔离,合成气环境、地磁场缺失、温度与气压波动等).本文详细介绍了这些因素对植物的影响.     

3D回旋仪模拟微重力效应对小鼠骨骼和 心脏的影响

目的：利用3D 回旋仪模拟微重力效应探究对小鼠骨骼和心脏的影响。方法：25 只8 周龄雄性C57BL/6J 小鼠,随机分成5 组（n=3~5）：地面对照组（GC 组）,3 周处理对照组（TC3 组）,3 周模拟微重力组（SM3 组）,6 周 处理对照组（TC6 组）,6 周模拟微重力组（SM6 组）。使用Micro-CT 检测小鼠左股骨参数变化。采用超声方法检 测小鼠心脏结构和功能的变化。结果：与GC 组相比,TC3 组、SM3 组、TC6 和SM6 组小鼠的骨体积分数,骨小 梁厚度显著降低（P<0.05）,骨小梁间距显著增加（P<0.05）。骨小梁数量和皮质骨壁厚度没有显著性差异。3D 回 旋仪处理3 周后,与小鼠左心室后壁厚度变薄相比,其他参数没有变化。而在第6 周,舒张期和收缩期的左心室 内径变小,左心室质量变轻。结论：3D 回旋仪模拟微重力效应会导致小鼠骨质流失,影响心脏结构和功能,且具 有时间效应。