Experimental determination of hydrogen bandwidth for the ion parametric resonance model

The ion parametric resonance (IPR) model predicts that distinct patterns of field-induced biological responses will occur at particular magnetic field combinations which establish ion resonances. An important characteristic o f resonance is the bandwidth response of the system, in part because it det ermines the required tolerances of the test system. Initial development of the IPR model used literature data to estimate the bandwidth for any ion re sonance to be +/-10% of its exact resonance. Because the charge-to-mass rat io of hydrogen is much larger than any other biologically significant ion, hydrogen resonance provides a unique test case by which a single ionic band width can be clearly measured. Of particular relevance is work by Trillo et al. that demonstrated a hydrogen-only, resonance-based IPR response of neu rite outgrowth in PC-12 cells. The work reported here considers the respons e of nerve-growth-factor-stimulated PC-12 cells exposed to magnetic fields tuned at or near hydrogen resonance. This work was designed to test directl y the IPR model hypothesis of a +/- 10% ionic bandwidth. Consistent with th e work of Trillo et al., resonance conditions were established using a 2.97 mu T static magnetic field, and the AC frequency and field strength were v aried to prove different aspects of the resonance. With this static field 4 5 Hz was the resonance frequency identified for hydrogen, 42.5 and 47.5 Hz were near-resonance frequencies, and 40 and 50 Hz bounded the assumed +/-10 % hydrogen resonance bandwidth. We repeated each test three times. The cell responses at 45 Hz exposures agreed with the IPR model predictions and rep licated results obtained by Trillo et al. Cells exposed to 42.5 and 47.5 Hz (near resonance) magnetic fields responded in the same general pattern as those exposed to 45 Hz fields, but neurite outgrowth was less than that obs erved at resonance. Measured results for cells exposed to either 40 Hz or 5 0 Hz fields were indistinguishable from off-resonance responses, consistent with the hypothesized bandwidth. These results confirm that the response b andwidth for the hydrogen ion is no greater than +/-10%, and give further s upport to the resonance-based predictions of the IPR model. (C) 1999 Wiley- Liss, Inc.