中文摘要：

目的探讨周期性张应力对体外培养的小鼠胚胎成纤维细胞增殖特性的影响。方法将体外培养的L929细胞分为加力组与对照组,加载周期性张应力的细胞为加力组,不加力的为对照组。应用细胞应力加载系统对L929细胞加载8%形变率、0.1 Hz的周期性张应力,分别在加力1 h、2 h、4 h和8 h后应用流式细胞仪分析细胞周期;四甲基偶氮唑盐比色法分析细胞的增殖活性。结果加力组加力1 h（q=5.532,P〈0.01）与2 h（q=6.569,P〈0.01）,S期细胞比率（S-phase fraction,SPF）较对照组出现了下降,并伴有细胞数量的增加（P〉0.05）;加力组在加力4 h后,SPF较对照组下降（P〉0.05）,细胞数量增加（P〉0.05）;加力组在加力8 h后,SPF较对照组开始出现增高（q=4.287,P〈0.05）,细胞数量显著增加（q=5.202,P〈0.01）。结论 8%形变率、0.1 Hz的周期性张应力引起细胞增殖活性的变化,表现为随应力加载时间的延长,细胞的增殖活性出现先被抑制、后被促进的改变。

英文摘要：

Objective To study the effect of cyclic tensile stress on proliferation of mouse embryonic fibroblasts.Methods Cell tensile stress application system were used to apply 0.1 Hz cyclic tensile stress,on the L929 cells for1 h,2 h,4 h,and 8 h separately,the tensile stress applied caused 8% deformation of basement membrane.The percentage of cell cycle changes were observed with flow cytometry analysis,and the changes on proliferation were analysed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl-2H-tetrazoliumbromide（MTT）.Results The S-phase fraction（SPF） of fibroblasts subjected to stress for 1 h and 2 h group decreased comparing to control group（P0.01）,and the count of fibroblasts increased（P0.05）;The SPF picked up after the fibroblasts subjected to stress for 4 hours（P0.05）.It was lower than the control group（P0.05）.The count of fibroblasts increased（P0.05）.Both the SPF and the count increased excessively after the fibroblasts subjected to stress for 8 hours（P0.05,P0.01）.Conclusion Cyclic tensile stress（8%,0.1 Hz） changed the proliferation of fibroblasts.It showed that a restrained effect in early stage and an accelerated effect in later phase comply with the stress in the fibroblasts.