【摘要】 为证实失重后航天员的超重耐力下降是否与失重引起的血循环系统的紊乱有关，观察了２７只白兔在头低位－２０°倾斜前后，－４Ｇｘ作用下的超重耐力、微循环和血液流变性变化。结果表明，模拟失重兔的－４Ｇｘ超重耐力明显下降，并出现了微循环和血液流变性的改变。微循环的改变表现为微血管管径增加、流速减慢、流量增加、红细胞聚集和血球血浆分离。血液流变性的变化为血粘度、纤维蛋白原、血细胞压积、红细胞聚集指数均增高。所以，模拟失重所引起的微循环和血液流变性改变有可能是造成超重耐力下降的主要起因之一。更多还原

【Abstract】 The direct consquetice of cardiovascular adaptation to weightlessness(WL)is the decreaseof G tolerance. In studying the mechanism of G tolerance after WL, respiration, heart rate, electrocar-diogram, temporal arterial flow, loss of vision were usually used as the indices for evaluation of G tol-erance. However the changes of microcirculation and blcod rheological indices were seldom observed.Considering that the changes of status of blood circulation after WL may be one of the important fac-tors causing decrease of G tolerance,microcirculatory and blood rheological changes in rabbitsduring-Gx stress after exposure to simulated weightlessness( SWL)were observed.The subjects were 27 male rabbits. Head down 20°was used to simulate WL,and-Gx tolerancewas determined on a centrifuge.The result showed that-Gx tolerance of rabbits after SWL was generally decreased.It was char-acterized by disappearance of flucturating type or accelerating type and increase of decreasing or bipha-sic types of heart rate under-4Gx stress in rabbits after SWL. In the same time,the disorder of mi-crocirculation and blood rheological indices after-4Gx stress were significant in rabbits after SWLthan that in normal rabbits. The disorder of microcirculation were characterized by increase of bore ofmicrovesseles and volume of blcod flow,decrease of speed of blood flow,increase of red cell aggrega-tion and separation of cells and plasma. The changes of blood rheological indices were characterized bythe increase of blood viscosity,fibrinogen,hematocrit and index of red cell aggregation.The results suggest that the disorderof microcirculation and blood rheological indices caused byWL might be the factors causing G intolerance after WL. G intolerance after WL might be influencedby changes in circulatary status in three ways:1.changing the morphology and function of main or-gans.2.decreasing the ability of oxygenation.3. decreasing the effective circulatory blood Volume.更多还原