The phosphorylation of stress-activated protein kinase was measured. Cells were exposed in the two intensitiy groups. Every intensity group was divided into eight duration subgroups (3, 5, 10, 15, 30 min and 1, 12, 24 h), and a sham exposure group. All subgroup cells were harvested at the same time (4 days after beginning of exposure).
|Setup||3 square Helmholtz coils (36 cm x 8 cm) with 168, 60, 168 (upper, middle, lower coil) turns of 1.16 mm copper wire, connected in series, set up inside an iron-shielded box inside a CO2 incubator; culture bottles placed in the central area between the coils|
|Sham exposure||A sham exposure was conducted.|
Both 0.4 mT and 0.8 mT could induce the phosphorylation of stress-activated protein kinase. The phosphorylation of stress-activated protein kinase presented a time-dependent course. The phosphorylated stress-activated protein kinase enhanced its enzymatic activity.
All the data indicated that 50 Hz electromagnetic field could activate stress-activated protein kinase in a time- and intensity-dependent manner. The biological effects caused by 50 Hz electromagnetic fields may be related to the stress-activated protein kinase signal transduction pathway.