Jr. Jauchem et Mr. Frei, HIGH-PEAK-POWER MICROWAVE PULSES - EFFECTS ON HEART-RATE AND BLOOD-PRESSURE IN UNANESTHETIZED RATS, Aviation, space, and environmental medicine, 66(10), 1995, pp. 992-997
Introduction: Exposure sources capable of generating high-peak-power m
icrowave pulses, with relatively short pulse widths, have recently bee
n developed. Studies of the effect of these sources on the cardiovascu
lar systems of animals have not been reported previously. Methods: We
exposed 14 unanesthetized male Sprague-Dawley rats to 10 high-peak-pow
er microwave pulses generated by a transformer-energized megawatt puls
ed output (TEMPO) microwave source, at frequencies ranging from 1.2-1.
8 GHz. Peak power densities were as high as 51.6 kW/cm(2). At 14 d pri
or to irradiation, the animals were implanted with chronic aortic cann
ulae. With appropriate shielding of the transducer, blood pressure rec
ordings were obtained during microwave pulsing. Results:ln a prelimina
ry series of exposures at 1.7-1.8 GHz (peak power density 3.3-6.5 kW/c
m(2)), an immediate but transient increase in mean arterial blood pres
sure (significant) and decrease in heart rate (non-significant) were o
bserved. A loud noise was associated with each pulse produced by the T
EMPO; this factor was subsequently attenuated. In a second series of e
xposures at 1.2-1.4 GHz (peak power density 14.6-51.6 kW/cm(2)), there
were no significant changes in mean arterial blood pressure or heart
rate during microwave exposure. Conclusions: The earlier significant i
ncrease in blood pressure that occurred during microwave exposure appe
ared to be related to the sharp noise produced by the TEMPO source. Af
ter appropriate sound attenuation, there were no significant effects o
f exposure to the microwave pulses.