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Modification of Heart Function with Low Intensity Electromagnetic Energy
Abstract
Three groups of frogs were exposed to pulsed modulated radio frequency electromagnetic (EM) energy. One group was subjected to alternating ten-minute periods of energy exposure and sham exposure, with the exposure pulses synchronized with the rise of the R-wave. A second group was subjected to alternating ten-minute periods of energy exposure and sham exposure, with the exposure pulses synchronized with the T-wave. The third group was sham-exposed controls. The data indicated that rate of change of beat is influenced by exposure to EM energy at incident average power densities of 3 micro-watts/cm. Synchronization of the energy pulses with the phase of the cardiac cycle is of consequence.
Euphorbia larica Boiss is a wild plant of Oman that grows in gravel plains, mountain areas, desert and forest edges. Traditionally, Omani herbalists use the Euphorbia larica plant extract, resins, latex and juice to treat a wide range of ailments such as wounds, burns, insect bites, intestinal parasites, gonorrhea, eye infections, migraines and warts. In an attempt to scientifically validate the traditional uses and to unlock its hidden therapeutic potential, in this work, the chemical composition of E. larica essential oil (ELEO) along with its potential antioxidant, antimicrobial and hemolytic activities is studied. In a GC-MS analysis of the extracted ELEO, 29 chemicals were found, with α-pinene (27.36%) and limonene (11.5%) being the two most abundant volatile components. ELEO exhibited moderate inhibition of DPPH radicals (17.74-40.96%; IC50 = 48.97 μg/mL). It showed antimicrobial activity against S. aureus, B. subtilis, S. pyogenes, E. coli, P. aeruginosa and P. vulgaris but was ineffective against K. pneumoniae bacterial strain however, exhibited the maximum antibacterial activity against S. aureus (11 ± 1.3 and 15 ± 2.3 mm at 5 and 10 μL concentrations, respectively) comparable to positive antibiotic ampicillin (15 mm at 5 μg). Moreover, ELEO exhibited a very low hemolytic activity (0.12 to 1.1% at doses of 50-500 μg) suggesting it to be non-toxic to human or animal cells. Thus, it can be concluded that E. larica plant holds significant potential as a source of bioactive agents for the development of novel therapeutics.
Inter-beat intervals of aggregated cardiac cells from chicken embryos were studied during 190s exposures to 2.45 GHz microwaves in an open-ended coaxial device. Averaged specific-absorption rates (SARs) and modulation conditions were 1.2-86.9 W/kg continuous-wave (CW), 1.2-12.2 W/kg pulse modulation (PW, duty cycle [approximately] 11%), and 12.0-43.5 W/kg square-wave modulation (duty cycle = 50%). The inter-beat interval decreased during microwave exposures at 42.0 W/kg and higher when CW or square-wave modulation was used, which is consistent with established effects of elevated temperatures. However, increases in the inter-beat interval after PW exposures at 8.4-12.2 W/kg, are not consistent with simple thermal effects. Analysis of variance indicated that SAR, modulation, and the modulation-SAR interaction were all significant factors in altering the interbeat interval. The latter two factors indicated that the cardiac cells were affected by athermal as well as thermal effects of microwave exposure.
Calcium efflux from electrically stimulated, 45Ca(2+)-preloaded atrial strips of the frog heart was measured from samples of the rinsing perfusate collected at 2-min intervals for 32 min in a continuous perfusion chamber. Contractile force was simultaneously monitored. The specimen chamber was located in a stripline apparatus in which the atrial strips were exposed for 32 min to constant (CW) or amplitude-modulated (AM), 1 GHz electromagnetic (EM) fields at specific absorption rates (SAR) ranging from 3.2 microW/kg to 1.6 W/kg. Amplitude modulation was either at 0.5 Hz, in synchrony with the electrical stimulus applied to the preparation, or at 16 Hz. Neither unmodulated nor 0.5 Hz or 16 Hz modulated 1 GHz waves affected the movement of calcium ions or the contractile force in isolated atrial strips of the frog heart.
Effects of intermittent exposure to 5.6-GHz radiofrequency radiation (RFR) on heart rate, blood pressure, and respiratory rate were examined in anesthetized rats. During exposure to 60 mW/cm2 which resulted in a 1 degree C change in colonic temperature, heart rate increased; the values returned to control levels after exposure was discontinued. No changes in mean arterial blood pressure or in respiratory rate were observed. Exposure to 30 mW/cm2 caused no significant changes in heart rate, blood pressure, or respiratory rate. The data indicate that heart rate changes during exposure to 5.6-GHz RFR are related to the average power density applied, and thus to the rate of change in temperature, and not simply to the absolute change in temperature.
Isolated frog hearts were irradiated with pulse modulated microwave energy synchronized with the ECG. No statistically significant or otherwise observable differences were found between the heart rate of irradiated groups and the nonirradiated control group. Experiments were performed to explore the possible effects of currents induced between the recording electrodes. Increases in heart rate occurred when applied current pulses between 20 and 30 mA were synchronized with the ECG during an interval from 200 msec to 300 msec after the peak of the P wave.
Each of three adult New Zealand rabbits, 2 male and 1 female albinos, was exposed dorsally or ventrally, to 2450-MHz plane waves for 20 min under each of several field conditions: 1) to continuous waves (CW) at 5 mW/cm2; 2) to pulsed waves (PW) of 1-microsecond width that recurred 700 pps at an average of 5 mW/cm2 and at a peak of 7.1 W/cm2; 3) to PW of 10-microseconds width at a peak of 13.7 W/cm2 that were synchronized with and triggered by the R wave of the electrocardiogram (EKG) at various delay times (0, 100, and 200 ms; and 4) to CW at 80 mW/cm2. Carbon-loaded Teflon electrodes were used to record the EKG from forelimbs of an animal before, during, and after irradiation whilst it was maintained in a constant exposure geometry in a wooden squeeze box. Field induced changes in the heart-beat rate were observed at 80 mW/cm2 but not a lower average power densities, although a peak positive chronotropic effect might have been occasioned by PM introduced at 100 and 200 ms after the R wave peak. No cumulative effect was observed over a period of four months. Thermographic analysis revealed relatively little absorption of microwave energy by the myocardium irrespective of anatomical aspect of exposure.
Microwave irradiation at 960-MHz CW of isolated poikilothermic hearts in Ringer's solution causes bradycardia. Tachycardia is usually produced by generalized heating, suggesting the possibility of a different mechanism in this case. The effect occurs only over a narrow power range of approximately 2-10 mW/g absorbed by the heart. It is hypothesized that microwave radiation causes neurotransmitter release either by excitation of the nerve remnants in the heart, or by some other mechanism, producing bradycardia over a restricted range of power absorption. Drugs which can change the response of the heart to transmitter substances have been used, and the results support a neurotransmitter release hypothesis. A generalized heating effect, causing tachycardia, is predominant at higher levels of absorbed power.
Continuous 960-MHz microwave irradiation of isolated poikilothermic hearts in Ringer's solution causes bradycardia, in contrast to the tachycardia usually produced by generalized heating. The effect appears to occur only over a narrow power range in the neighborhood of an estimated 3 mW absorbed by the heart. It is hypothesized that the bradycardia is produced by stimulation of the nerve remnants in the heart.
Action of a Low Intensity Pulsed Super-High Frequency Electromagnetic Field on Heart Contraction Rhythm in the Frog. All-Union Symposium on the Biological Effects of Electromagnetic Fields
- R E Tigranian
- A S Parsadanian
Non-Contact Measurement of Microwave Induced Changes in Frog Heart Beating Rhythms
- R Chalker
- H Wachtel
- F Barnes
Effects of Low Frequency Amplitude Modulation Radiofrequency Waves on the Calcium Efflux of the Heart
- J L Schwartz
- J Delorae
- G A R Mealing
Effects of Microwave Exposure on Frog's Heart Rate in vitro
- K C Yee
- C K Chou
- A W Guy