中文摘要：

目的研究50 Hz工频磁场诱导细胞膜表面表皮生长因子（EGF）受体聚簇与酸性鞘磷脂酶（acid sphingomyelinase，A-SMase）以及神经酰胺（ceramide）之间的关系，探索工频磁场诱导细胞膜受体聚簇的可能机制。方法将人羊膜上皮细胞（FL）暴露于50Hz、0．4mT工频磁场15min，设立假辐照组和EGF阳性对照组，同时各组分别设立常规培养组、丙咪嗪（imipranfine）、二甲亚砜（DMSO）以及神经酰胺预处理组。处理后的细胞采用间接免疫荧光技术，以抗体标记EGF受体。制片后通过激光共聚焦显微镜对其聚簇情况进行观察分析。结果EGF阳性对照组和50Hz磁场处理组均能观察到明显的EGF受体聚簇现象；当以丙咪嗪预处理4h后，EGF阳性对照组和磁场处理组中受体聚簇现象明显减弱。而在丙咪嗪预处理后再加入神经酰胺预处理30min时，EGF阳性对照组和磁场处理组中受体聚簇现象又呈现明显的恢复。结论工频磁场诱导FL细胞膜表面EGF受体聚簇与A—SMase的活力密切相关，神经酰胺作为A—SMase的水解产物可能参与了工频磁场诱导的受体聚簇。

英文摘要：

Objective To investigate the relationship among a 50-Hz MF-induced epidermal growth factor receptor （EGFR） clustering, acid sphingomyelinase （A-SMase） and ceramide （CER）, and to explore the possible mechanism of receptor clustering. Methods Human amnion （FL） cells were exposed to a 50-Hz sinusoidal magnetic field at 0.4 mT for 15 rain with or without imipramine, a specific inhibitor of A-SMase and eeramide pretreatment. EGF treatment served as the positive control and DMSO treatment served as the solvent control. The EGFR was labeled with polyclonal anti-EGFR antibody and the clustering of EGFR was analyzed using immunofluorescence and confocal microscopy. The percentage of ceils with EGFR clustering was counted and compared. Results Both EGF treatment and 50-Hz MF exposure could induce EGFR clustering. However, the effect could be eliminated by imipramine pretreatment for 4 hours. When FL ceils were incubated with ceramide following the imipramine pretreatment for 30 rain, EGFR clustering induced by 50-Hz MF exposure could be recovered. Conclusion EGFR clustering induced by 50-Hz MF depends on A-SMase activity, and ceramide, as the hydrolyzate from A-SMase might participate in the process of EGFR clustering.