title: A rat liver foci promotion study with 50-Hz magnetic fields.
abstract: To investigate the possible tumor-promoting effect of magnetic fields (MF), we have performed two liver foci bioassays in rats which were exposed to MF at four flux density levels (0.5 microT, 5 microT, 0.05 mT, and 0.5 mT). The MF were generated in exposure equipment consisting of copper coils surrounding racks with animal cages and giving homogenous horizontal 50-Hz magnetic fields. Rats previously submitted to partial hepatectomy and diethylnitrosamine treatment were exposed to MF for 12 weeks. Exposed and control rats were kept in separate rooms. As a positive control phenobarbital (PB) was administered for 12 weeks. The number, area, and volume of foci expressing gamma-glutamyl transpeptidase (GGT) and glutathione S-transferase (GST-p) were evaluated. The body weight gains and relative liver weights of MF-exposed rats were not different as compared to control rats. There was a slight increase in GGT-staining foci, but not in GST-p-staining foci, in the groups exposed to flux densities of 0.5 microT and 0.05 mT compared to the control group in the first experiment. The number of both GGT- and GST-p-staining foci in the livers of all MF-exposed groups were, however, within the control range when the results of the two experiments were considered together.
authors.affiliation: Department of Toxicology, National Institute of Occupational Health, Solna, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Rannug
authors.forename: B
authors.initials: B
authors.lastname: Holmberg
authors.forename: K H
authors.initials: KH
authors.lastname: Mild
mesh_terms: D000818:Animals; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005982:Glutathione Transferase / Q000032:analysis*; D006498:Hepatectomy; D008099:Liver / Q000201:enzymology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D005723:gamma-Glutamyltransferase / Q000032:analysis*
chemical_list: D005723:gamma-Glutamyltransferase; D005982:Glutathione Transferase