Microwave influence on the isolated heart function: I. Effect of modulation

Abstract

Dependence of the microwave effect on modulation parameters (pulse width, duty ratio, and peak intensity) was studied in an isolated frog auricle preparation. The rate and amplitude of spontaneous auricle twitches were measured during and after a 2 min exposure to 915 or 885 MHz microwaves and were compared to preexposure values. The studied ranges of modulation parameters were: pulse width, 10(-6)-10(-2) s; duty ratio, 7:100000, and peak specific absorption rate, 100-3000 W/kg. Combinations of the parameters were chosen by chance, and about 400 various exposure regimes were tested. The experiments established that no regime was effective unless the average microwave power was high enough to induce preparation heating (0.1-0.4 degree C). The twitch rate instantly increased, and the amplitude decreased, as the temperature rose; similar changes could be induced by equivalent conventional heating. The data provide evidence that the effect of short-term microwave exposure on the isolated heart pacemaker and contractile functions depends on pulse modulation just as much as modulation determines the average absorbed power. These functions demonstrated no specific dependence on exposure parameters such as frequency or power windows.

Comparative effects of extremely high power microwave pulses and a brief CW irradiation on pacemaker function in isolated frog heart slices

“…Within limits of the study, EHPP and LPP effects were not indicative of any interaction mechanisms other than general heating. This conclusion is consistent with our earlier studies in frog heart slices, despite differences in exposure and beat recording techniques, radiation frequencies, powers, and pulsing regimes [Pakhomov et al, 1995[Pakhomov et al, , 1999a.…”

No Effects of Pulsed High-Frequency Electromagnetic Fields on Heart Rate Variability during Human Sleep¹

“…Pakhomov et al [31,32] reported that microwave exposure has no effect on spontaneous twitches of frog auricle preparations unless absorbed power was high enough to induce heating. Watkinson and Gordon [33] found a linear correlation between heart rate and deep body temperature in rats under exposure to radiofrequency radiation.…”

Comparison of dose dependences for bioeffects of continuous‐wave and high‐peak power microwave emissions using gel‐suspended cell cultures†

“…To add more complications, some speci®c effects required a precise combination of different exposure parameters, e.g., the carrier frequency and pulse repetition rate [Gapeev et al, 1994;Semin et al, 1995b] or the modulation frequency and the radiation intensity [Blackman et al, 1980;Adey, 1988;Dutta et al, 1989;Schwartz et al, 1990]. Since the windows often are very narrow, the experimental search for unique combinations of different exposure parameters among the innumerable possibilities is problematic, and it is no wonder that many attempts to reveal the effectiveness windows by probing various combinations of exposure parameters resulted in negative ®ndings [Chou and Guy, 1978;Bush et al, 1981;Liu et al, 1982;Pakhomov et al, 1992Pakhomov et al, , 1995. More information and discussion of window phenomena can be found in specialized reviews on pulsed microwave bioeffects [Blackwell and Saunders, 1986;Postow and Swicord, 1986;Pakhomov and Murphy, 2000].…”