The coaxial cell exposure chamber was a mechanically modified version of the system described in [Guy, 1977]. It consisted of an annular region having a volume of 5 ml with stainless steel walls (3.34 and 3.84 cm radius) and a Teflon bottom. Samples could be exposed to relatively uniform (15% variation) electric field strengths at temperatures controlled using a high-rate circulating-liquid heat exchanger which allowed duplicating the temperature history of RF- and sham-exposed samples.
Two samples were RF and sham exposed in identical exposure chambers at 22.5 ± 0.2 °C. A third sample was sham exposed at 20 ± 0.1 °C in an incubator, primarily as a reference for K+ release [Cleary et al., 1982]. A fourth control sample in a capped standard 10-ml plastic culture tube was placed together with the third one. All exposures were performed simultaneously. The interior surfaces of the RF chambers and culture tubes were siliconised prior to each experiment.
Fixed position probes and a vector voltmeter were used for monitoring the electric and magnetic field strength and for calculating the complex impedance of the sample. The sample conductivity derived from the dielectric constant was used to calculate the SAR in the sample.