Epidemiological studies indicating a role for extremely low frequency electromagnetic fields (ELF-EMF) in the etiology of Alzheimer's disease (AD) provided an impetus for biological investigation. An in vitro approach was undertaken utilizing a human neuroblastoma (IMR-32), a model cell line in AD research. IMR-32 cells differentiated with 5-Bromo deoxy uridine were characterized with respect to morphological, biochemical (neuron specific enolase) and electrophysiological (resting membrane potential [Vm] development) differentiation markers. Biochemical and morphological differentiation markers were used to identify distinct differentiation ages for application as an experimental variable in future studies. | In order for an exposure system to constitute a uniform criterion across different experimental approaches, a controlled system for studying cellular responses to ELF-EMF exposure was designed and evaluated. The parameters considered for evaluation involved linear magnetic field distribution, compensation for microscope objective lens interference, heating effects of the coils, and harmonic contents of the signals. The system was found to be feasible for measuring real time biological changes (e.g., Vm) as well as for gene transcription studies, which involve longer exposure times traditionally conducted in cell culture incubators. An application of the system to study the effect of ELF-EMF on Vm in differentiating IMR-32 cells revealed a depolarization effect, attributed to a possible increase in Na+-K+-ATPase activity. | Northern analysis was used to evaluate the APP695 transcription levels in IMR-32 cells in response to power frequency (60 Hz) electromagnetic field exposure. Double-blind experiments were conducted in which IMR-32 cells were exposed to magnetic field intensities of 50, 100 or 200 ?T (microtesla) for a period of four hours at the three ages of differentiation (2, 10, 16 days after incubation in differentiation medium). The results indicated that neither differentiation age nor magnetic field intensity had any effect on APP695 gene transcription in IMR-32 cells. These studies constitute a first step towards investigating the plausibility of an association between ELF-EMF exposure and AD manifestations at the cellular level.