Microwave influence on the isolated heart function: II. Combined effect of radiation and some drugs

Abstract

The combined effects of microwave radiation and some drugs were studied in an isolated frog auricle preparation. The experiments established that exposure to pulse-modulated 915 MHz microwaves for up to 40 min had no effect on either the rate or the amplitude of spontaneous auricle twitches, unless the average absorbed power was high enough to produce preparation heating. Treatment of the preparation with saline containing (0.6-3.0) 10(-5) M of propranolol or (0.5-1.5) 10(-7) M of atropine altered neither its pacemaker nor its contractile functions; these drugs also had no effect when they were combined with nonthermal microwave irradiation. Caffeine (1 mM) strongly increased the average heart power, which was calculated as the product of twitch rate and amplitude. The caffeine effect appeared to be significantly augmented (by about 15%, P < 0.02) under exposure to burst-type pulsed microwaves (pulse width, 1.5 msec; pause, 2.5 msec; 8 pulses/burst, 16 bursts/s; average SAR, 8-10 W/kg). By itself, this modulation was not effective; the heating of the preparation and saline during exposure was approximately 0.1 degrees C, which could not account for the detected changes. The experimental results demonstrate that caffeine treatment increases the microwave sensitivity of the frog auricle preparation and reveals primarily subthreshold, nonthermal microwave effect.

Biological effects of amplitude-modulated radiofrequency radiation

“…Exposure of frog hearts for 2 hours to pulsed 2.45-GHz microwaves (10 ps, 111000 duty cycle, 16-Hz modulation, SAR 0.003, 2 or 6 Wlkg) did not modify conduction velocity (16). Although Pakhomov et a1 (17) did not find any effects on the twitch rates and amplitudes of isolated Rana temporaria frog auricles when PM 915-MHz microwaves at SAR values below 10-20 Wlkg were applied alone, they observed an increase in both these parameters after sensitization by 1-mM caffeine added to the saline flow system.…”

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.…”

Services to Operate and Maintain the Microwave Research Facility at Brooks Air Force Base, San Antonio, Texas

“…In contrast, the same irradiation for 10 min at 2-3 mW/cm 2 decreased the heart arrest latency by 10-25%. Pakhomov et al (1995b) attempted to replicate findings of Tinney and co-authors (1976) that microwaves can cause beating rate changes in isolated heart by stimulation of ncurotransmittcr release from autonomous nervous system introcardiac fiber terminals. CW exposure at 2-10 mW/g (960 MHz) was reported to cause bradycardia in isolated turtle hearts.…”

“…Therefore, Pakhomov et al (1995b) inferred that caffeine itself could enhance the microwave effect and tested this hypothesis in isolated frog heart slices. In contrast to atropine and propranolol, superfusion of slices with 1 mM of caffeine strongly increased the average heart power, which was calculated as a product of the beating rate and beats' amplitude.…”