1. Preliminary studies have established that cellular detection of EMF involves at least two important time scales: a rather short "sensing" interval, and a somewhat longer “memory” time. The temporal detection parameters will be thoroughly characterized, and the resultant data used to describe the cell-field interaction mechanism.

2. Experiments will examine the dose-response characteristics that determine cellular response to applied EMF. This will include an examination of amplitude thresholds for bio- response characteristics at various field frequencies, and an examination of what constitutes a "minimum effective dose" of field exposure.

3. Applied ELF noise fields with electric field amplitudes 100-1000 times smaller than those calculated for thermal noise fields have been shown to reduce, or to eliminate, the typical cellular response to applied 60 Hz magnetic fields. A series of EMF exposures will be conducted to explore the crucial differences, in terms of such inhibitory effects, between such externally impressed noise fields and the endogenous thermal noise fields.

2. Characterization of the Inhibitory Effects of superimposed EM noise fields: Our preliminary data have demonstrated that, under certain conditions, superimposing an incoherent (noise) EM field on a coherent EM field can inhibit the induction of bio-effects. We propose to explore extensively the parameters of the noise field which are crucial for inhibition effects. For example we shall consider such things as band width of noise, necessity for colinearity between coherent and incoherent fields, and time duration of noise. It is our hope to use this information to understand better how the cell discriminates against the local thermal noise fields and yet can be affected by an externally applied noise field which is 1,000 times smaller.

3. Determination of the Dose-Response relationship between the EMF and the bio-effect: Our preliminary data (and those of others in the literature) suggest that a rather sharp, dose-response amplitude threshold exists for induction of bioeffects by an EMF. Our first studies in this area will have as their goal the confirmation and characterization of these thresholds. In addition we propose to utilize the sharpness of the thresholds in a study of the frequency dependence of the threshold amplitude in order to explore the importance of the dielectric constant (and therefore of counter- ions) in the field-cell interaction mechanism.

Very uniform magnetic fields can be generated over large regions using paired coils arranged in the Helmholtz configuration. This arrangement uses two circular coils of equal radius, positioned parallel to each other at a distance equal to the radius. The coils are connected in series, with the current traveling in the same angular direction in both coils. The resulting magnetic field is substantially uniform within a portion of the volume between the coils. The regions of a Helmholtz coil within which the magnetic field varies by not more than 5% is roughly equal to 12% of the volume between the coils. This corresponds to a cylinder concentric with the axis of the coils, and with a diameter equal to 35% of the diameter of the coils.

Cell monolayers will be exposed in 75 cm2 tissue culture flasks containing 15 ml of nutrient medium. Three flasks will be stacked, one atop the other, and positioned within the Helmholtz coils such that the cell monolayers lie within a 2.5 radius concentric with the axis of the coils. A rectangular sample pattern will insure that the samples are correctly positioned within the Helmholtz coils. Each coil will be wound on a 15 inch aluminum form which will be electrically grounded. These coil dimensions insure that the magnetic field in the sample exposure region is within 5% of the axial field.

For the bulk of the proposed work we will use the activity of ornithine decarboxylase (ODC) to assess response to EM fields in the murine fibroblast cell line L929. Significant results obtained with L929 will be confirmed by limited replicate experiments using at least one other cell type. Such confirmation will be done using the Daudi human lymphoma line. When appropriate, we will also confirm the relevance of findings in cultured cells for an in vivo, multicellular system by investigating EMF-induced changes in ODC activity in chick embryos.

ODC analyses will be run in triplicate.