ID Number		473
Study Type		In Vitro
Model		2450 MHz (CW, PW) to frog nerves and analysis of firing duration
Details		Frog sciatic nerves were exposed to 2450 MHz (CW & PW-50 pps, pulse inverval 5 msec) at 10 W/kg in a waveguide exposure system and stimulated to fire (nerve vitality). Exposure to CW microwaves resulted in a prolonged refractory period and an amplitude decrease in action potential. Exposure to PW microwaves was found to decrease the length of time stimulated nerves would fire at a high rate (50 twin pulses/sec). PW exposure did not, however, affect survival time of isolated ouabain (Na+/K+ pump inhibitor) treated nerves. The authors suggest the effects observed on nerve vitality may be due to decay of ionic gradients normally maintained by active transport (a direct interference with the Na+/K+ pump by blocking the action of Na+/K+ dependent ATPase could be responsible for these effects). In earlier studies, Aplasia californica pacemaker neurons were exposed to 2450 MHz (CW & PW-0.5 usec duration at a repetition rate of 5000/sec) and 1500 MHz (CW) RF for short durations (on the order on minutes) at SARs of up to 400 W/kg. At SARs of 7W/kg or greater, the firing rate of about half of the pacemaker cells studied was slowly reduced, and reached a steady value after ~ 1 minute of exposure. Following exposure, this firing rate returned to pre-exposure levels in about 1-2 minutes. In addition, SARs of ~ 1 W/kg caused a few of the pacemaker cells to undergo a rapid increase in firing rate with exposure. The authors suggest microwaves might affect the membrane changing ionic conductance.
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		NIEHS - d.mcree@ix.netcom.com
Funding Agency		NIEHS, USA
Country		UNITED STATES
References		McRee, DI et al. Radiat. Res., (1982) 91:21-218 McRee, DI et al. Radiat. Res., (1986) 108:260-268 McRee, DI et al. Radiat. Res., (1980) 82:536-546 Wachtel, H et al. Ann. N.Y. Acad. Sci., (1975) 247:46-62
Comments		The effects of microthermal areas in the exposed tissue were not well addressed.