Investigation of Radiofrequency Radiation Effects on Excitable Tissues.
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GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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Spheroidal aggregates of cultured chick cardiac cells were used to study effects of 2450-MHz radiofrequency radiation RFR on excitable membranes. Rhythmically beating aggregates under normal culture conditions were exposed to known amounts of RFR energy in a specially developed open-ended coaxial device. Exposure level was given in terms of Specific Absorption Rate SAR in mWg. Short-term recordings with intracellular electrodes suggested that increased variability in beat rate and in action potential maximum upstroke velocity occurred in the range of 10-40 mWg for continuous wave CW RFR and RFR modulated as 10.9-microsecond pulses at 10,000 pps PW. Long-term recordings with extracellular electrodes and video imaging were used to gather interbeat interval IBI data for computing mean IBI and coefficient of variation CV. Three-minute exposures to CW and PW RFR and to RFR square-wave modulated at 1.6 or 16 Hz were made for SARs between 1.2 and 85.5 mWg. Decreases in mean IBI during exposure for SARs greater than 30 mWg closely matched those expected from induced temperature rises. However, IBI changes at smaller SARs, including an increase at 1.2 mWg, were not fully explained by temperature changes. Small changes in CV occurred during exposure and were similar to those during sham exposures.