Effects of a static magnetic field on proliferation, apoptosis and secretion in human umbilical cord endothelial cells

Abstract

Objective To evaluate the effects of static magnetic fields (SMFs) of different intensity and exposure duration on the proliferation and apoptosis of human umbilical cord endothelial cells (HUVECs),and their release of nitric oxide (NO),6-keto-prostacyclin 1α (6-keto-PGF1α) and endothelin (ET-1).Methods Cultured HUVECs were exposed to a SMF at 5,22,86 or 135 mT for 8,12 or 24 hours.Their proliferation and apoptosis were monitored by flow cytometry (FCM).The medium was collected to test its NO content by optical density.ET-1 and 6-keto-PGF1α were measured by radioimmunization.Results ( 1 ) The proliferation of HUVECs increased when the cells were exposed to a SMF at 5 mT for 8 h,but a SMF at 135 mT for 12 h or 24 h inhibited the proliferation of HUVECs.(2)An SMF had no effect on apoptosis of HUVECs.(3)An SMF at 5 mT for 8 h increased the release of NO and 6-keto-PGF1 a,but the release of NO and 6-keto-PGF1 a decreased when the SMF intensity was 135 mT or the cells were exposed to an SMF for 12 h or 24 h.(4) An SMF at 5 mT or 22 mT for 8 h did not effect the release of ET-1.An SMF at 86 mT or 135 mT increased the release of ET-1.Compared with a control group,an SMF at 5 mT for 12 or 24 h did not affect the release of ET1,but at 22,80 or 135 mT,the release of ET-1 decreased significantly.Conclusions Exposure to a low intensity SMF for a short duration could improve the proliferation of HUVECs and increase the release of vasoactive factors,but if HUVECs are exposed to a strong SMF or exposed for a long duration,the proliferation and the release of vasoactive factors is decreased. Key words: Static magnetic fields; Endothelial cells; Nitric oxide; Endothelin-1; 6-keto-prostacyclin 1 α