Objective: To determine the effects of intermittent hypoxia (IH )on the growth of SW480 cell lines and the expression of hypoxia-inducible factor(HIF)-1α

the phenomenon of IH in tumors and the relation between IH and HIF-1α were discussed. Methods: The hypoxia condition was simulated by CoCl2. Effect of IH on the growth of SW480 cell lines was observed by MTT assay. Effects of IH on the expression of HIF-1α were analyzed by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) and Western blot assay. Cells were divided into four groups: group A: normoxia group

group B: IH for 2 hours group

group C: IH for 3 hours group

and group D: continuous hypoxia (CH) for 3 hours group. Results: MTT assay indicated that in the 3 hypoxia groups

the growth of SW480 cell lines was inhibited

when compared with normoxia group. The growth of SW480 cell lines was also inhibited in group C and group D when compared with group B. No significant differences were observed between group C and group D.RT-PCR showed that the level of HIF-1α mRNA in group C was higher than that in group A

group B and group D. No significant differences were observed among the other 3 groups. Western blot found that the level of HIF-1α protein in group C was higher than that in the other 3 groups.The level of HIF-1α protein in group D was higher than that in group B and group A. No significant differences were observed between group B and group A. Conclusion: Same hypoxia time but different hypoxia manner inhibit the growth of SW480 cell lines to the same degree. A certain degree of IH can up-regulate the mRNA and protein level of HIF-1α.