SUSPENSION OSTEOPENIA IN MICE - WHOLE-BODY ELECTROMAGNETIC-FIELD EFFECTS

Whole-body fields were tested for their efficacy in preventing the ost eopenia caused by tail suspension in mice. The fields had fundamental frequencies corresponding to the upper range of predicted endogenous i mpact-generated frequencies (0.25-2.0 kHz) in the long bones. Three di stinct whole-body EMFs were applied for 2 weeks on growing mice. Struc tural, geometric, and material properties of the femora, tibiae, and h umeri of suspended mice were altered compared to controls. Comparison of suspended mice and mice subjected to caloric restriction indicates that the changes in caloric intake do not explain either the suspensio n or the field-induced effects. Tn agreement with past studies, rather , unloading appears to cause the suspension effects and to be addresse d by the EMFs. The EMF effects on bone properties were apparently freq uency dependent, with the lower two fundamental frequencies (260 and 9 10 Hz) altering, albeit slightly, the suspension-induced bone effects. The fields are not apparently optimized for frequency, etc., with res pect to therapeutic potential; however, suspension provides a model sy stem for further study of the in vivo effects of EMFs. (C) 1995 Wiley- Liss, Inc.