60-Hz electric fields: detection by female rats

Female rats were trained to detect a vertical, 60-Hz electric field using the same apparatus and procedure we used previously to study behavioral detection of the field by male rats. Each rat was trained individually to press a lever in the presence of the field and not to press in its absence. Correct detections occasionally produced a food pellet. The probability of detecting the field increased as field strength increased. The threshold of detection--ie, the field strength required for detections at a probability of 0.5 after correction for errors--varied among rats between 3 and 10 kV/m. Behavioral detection by female rats was indistinguishable from that by male rats.     

Detection of 60-hertz vertical electric fields by rats

Rats were trained to press levers to indicate the presence or absence of 60-Hz vertical electric fields at intensities from 0 to 27 kV/m (rms). The probability of detecting the field increased as the strength of the field increased. The shape of the detection curve (psychometric function) for most subjects (Ss) was similar whether the discriminative stimulus was the electric field or a tone. Two protocols were used to estimate the minimum field intensity necessary to detect the field (Reiz Limen, RL). The RL was estimated to be 13.3 kV/m (rms) when using one protocol (the staircase method) and 7.9 kV/m (rms) when using another protocol (the method of constant stimuli).     

Relationship between field strength and arousal response in mice exposed to 60-Hz electric fields

White-footed mice, Peromyscus leucopus, were exposed to 60-Hz electric fields to study the relationship between field strength and three measures of the transient arousal response previously reported to occur with exposures at 100 kV/m. Five groups of 12 mice each were given a series of four 1-h exposures, separated by an hour, with each group exposed at one of the following field strengths: 75, 50, 35, 25, and 10 kV/m; 8 additional mice were sham-exposed with no voltage applied to the field generator. All mice were experimentally naive before the start of the experiment, and all exposures occurred during the inactive (lights-on) phase of the circadian cycle. The first exposure produced immediate increases in arousal measures, but subsequent exposures had no significant effect on any measure. These arousal responses were defined by significant increases of gross motor activity, carbon dioxide production, and oxygen consumption, and were frequently recorded with field strengths of 50 kV/m or higher. Significant arousal responses rarely occurred with exposures at lower field strengths. Responses of mice exposed at 75 and 50 kV/m were similar to previously described transient arousal responses in mice exposed to 100-kV/m electric fields. Less than half of the mice in each of the field strength groups below 50 kV/m showed arousal responses based on Z (standard) scores, but the arousals of the mice that did respond were similar to those of mice exposed at higher field strengths. Polynomial regression was used to calculate the field strength producing the greatest increases for each of the arousal measures. The results show that the amplitude of the transient arousal response is related to the strength of the electric field, but different measures of arousal may have different relationships to field strength.     

Fusion of mitochondria

In this communication we reported the fusion of mitochondria of hepatocytes extracted from a rat liver. It was found that fusion occurred at an electric field of 1.56-1.8 kV/cm at room temperature. Further increase in the field strength (greater than 1.8 kV/cm) was accompanied by the breakdown of mitochondria.     

Effects of exposure to a 60-kV/m, 60-Hz electric field on the social behavior of baboons.

We found in a previously reported study that exposure to a 30-kV/m, 60-Hz electric field had significant effects on the social behavior of baboons. However, it was not established whether or not the effects were related specifically to the 30-kV/m intensity of the field. A new experiment was conducted to determine whether or not exposure to a 60-Hz electric field at 60 kV/m would produce like changes in the baboons' social behavior. We exposed one group of eight male baboons to an electric field 12 hours a day, 7 days a week, for 6 weeks. A second group of eight animals was maintained under sham-exposure (control) conditions. Rates of performing on each of six categories of social behavior and on four categories of nonsocial behavior were used as criteria for comparing exposed with unexposed subjects and for within-group comparisons during three six-week experimental periods: Pre-Exposure, Exposure, and Post-Exposure. The results indicate that (1) during the exposure period, exposed animals exhibited statistically significant differences from controls in means of performance rates based on several behavioral categories; (2) across all three periods, within-group comparisons revealed that behaviors of exposed baboons were significantly affected by exposure to the electric field; (3) changes in performance levels probably reflect a stress response to the electric field; and (4) the means of response rates of animals exposed at 60 kV/m were higher, but not double, those of animals exposed at 30 kV/m. As in the 30-kV/m experiment, animals exposed at 60 kV/m exhibited significant differences in performances of Passive Affinity, Tension, and Stereotypy. Mean rates of performing these categories were 122% (Passive Affinity), 48% (Tension), and 40% (Stereotypy) higher in the exposed group than in the control group during exposure to the 60-kV/m field.     

Calculation of internal from external electrical field strength and its effect on cardiac pacemaker patients]

What electric field strength is developed inside a person entering the electric field produced by, e.g., a high-voltage transmission line? This question may be of vital importance for a pacemaker patient. With the aim of finding an answer, known phenomena are combined in such a way that the mean current density within the thorax at the level of the heart can be determined. In this way it can be demonstrated that the internal electric field of a grounded person is twice that of an ungrounded person, that the internal field is 0.72 mV/m per 1 kV/m external field, and that the most sensitive pacemaker can be influenced by 2 kV/m. It is also clear that the field strength limit of 5 kV/m proposed by ICNIRP for the general public cannot be justified by the basic limit of 2 mA/m2.     

Dose response study of human exposure to 60 Hz electric and magnetic fields

This human exposure study examined the relationship between field strength and biological response and tested whether the exposure levels at which the greatest effects occur differ for different endpoints. Three matched groups of 18 men each participated in two 6 h exposure test sessions. All subjects were sham exposed in one session. In the other session, each group of subjects was exposed at a different level of combined electric and magnetic field strength (low group: 6 kV/m, 10 μT; medium group: 9 kV/m, 20 μT; and high group: 12 kV/m, 30 μT). The study was performed double blind, with exposure order counterbalanced. Significant slowing of heart rate, as well as alterations in the latency and amplitude of event-related brain potential measures derived from the electro encephalogram (EEG), occurred in the group exposed to the 9 kV/m, 20 μT combined field (medium group). Exposure at the other field strength levels had no influence on cardiac measures and differential effects on EEG activity. Significant decrements in reaction time and in performance accuracy on a time estimation task were observed only in the low group. These results provide support for the hypothesis that humans may be more responsive to some combinations or levels of field strength than to others and that such differences in responsivity may depend, in part, on the endpoint of interest. © 1994 Wiley-Liss, Inc.     

Comparison of 60-Hz electric fields and incandescent light as aversive stimuli controlling the behavior of rats

Rats were exposed to two procedures which enabled them to press a lever to turn off a 90 or 100 kV/m 60-Hz electric field or, later in the study, illumination from an incandescent lamp. Under one procedure, a response turned off the stimulus for a fixed duration, after which the stimulus was turned on again. A response during the off-period restarted the fixed duration. None of the rats turned the field off reliably. Next, under an alternative procedure, pressing one lever turned the field off; pressing the other lever turned it back on; responding under those conditions differed little from that seen at 0 kV/m. Under both procedures, when illumination from an incandescent lamp served as the stimulus, each rat did turn the stimulus off, and performances varied with stimulus intensity. The results show that a 100 kV/m 60-Hz electric field is not sufficient to function as an aversive stimulus under two procedures where illumination from a lamp does function as an aversive stimulus.     

60-Hz electric-field effects on pineal melatonin rhythms: time course for onset and recovery

Rats exposed for 3 weeks to uniform 60-Hz electric fields of 39 kV/m (effective field strength) failed to show normal pineal gland circadian rhythms in serotonin N-acetyl transferase activity and melatonin concentrations. The time required for recovery of the melatonin rhythm after cessation of field exposure was determined to be less than 3 days. The rapid recovery suggests that the overall metabolic competence of the pineal is not permanently compromised by electric-field exposure, and that the circadian rhythm effect may be neuronally mediated.     

60 Hz electric fields and incandescent light as aversive stimuli controlling the behavior of rats responding under concurrent schedules of reinforcement

Several reports have shown that animals will sometimes engage in behaviors that reduce their exposure to a 60 Hz electric field (E-field). The field, therefore, can function as an aversive stimulus. In other studies, the E-field at equivalent strengths failed to function as an aversive stimulus. The present experiment, using rats, demonstrates how factors other than field strength can influence whether a subject engages in behavior that reduces field exposure. The general design consisted of giving the rat a choice between two alternatives, one of which sometimes included an added stimulus. Each subject was trained to press each of two levers to obtain food. Pressing one lever was reinforced intermittently under a variable interval 2 min schedule (VI 2); pressing the other lever was reinforced by a second VI 2 schedule operating independently of the first. Under this concurrent schedule the rat spent 50% of the daily 50 min session responding to each of the levers, indicating that they were equally “valued.” Next, while the schedules remained in effect, the first response to one of the levers turned on a 100 kV/m E-field which remained on until the rat pressed the other lever. The time spent responding under the schedule associated with the field was reduced by about 5–10%. When the procedure was changed so that no lever presses produced food, i.e., extinction, but the added stimulus contingency remained, the rats spent even less time in the presence of the field. Similar outcomes were observed during both the concurrent food or extinction schedules when incandescent light was used. Thus, both an E-field and incandescent light functioned as aversive stimuli, but the magnitude of the aversiveness was small. Aversiveness depended not only on stimulus intensity, but also on behavioral factors. Bioelectromagnetics 19:210–221, 1998. © 1998 Wiley-Liss, Inc.     

Electrical hemolysis of human and bovine red blood cells.

The external electric field strength required for electrical hemolysis of human red blood cells depends sensitively on the composition of the external medium. In isotonic NaCl und KCl solutions the onset of electrical hemolysis is observed at 4 kV per cm and 50 per cent hemolysis at 6 kV per cm, whereas increasing concentrations of phosphate, sulphate, sucrose, inulin and EDTA shift the onset and the 50 per cent hemolysis-value to higher field strengths. The most pronounced effect is observed for inulin and EDTA. In the presence of these substances the threshold value of the electric field strength is shifted to 14 kV per cm. This is in contrast to the dielectric breakdown voltage of human red blood cells which is unaltered by these substances and was measured to be approximately 1 V corresponding in the electrolytical discharge chamber to an external electric field strength of 2 to 3 kV per cm. On the other hand, dielectric breakdown of bovine red blood cell membranes occurs in NaCl solution at 4 to 5 kV per cm and is coupled directly with hemoglobin release. The electrical hemolysis of cells of this species is unaffected by the above substances with exception of inulin. Inulin suppressed the electrical hemolysis up to 15 kV per cm. The data can be explained by the assumption that the reflection coefficients of the membranes of these two species to bivalent anions and uncharged molecules are field-dependent to a different extent. This explanation implies that electrical hemolysis is a secondary process of osmotic nature induced by the reversible permeability change of the membrane (dielectric breakdown) in response to an electric field. This view is supported by the observation that the mean volumes of ghost cells obtained by electrical hemolysis can be changed by changing the external phosphate concentration during hemolysis and resealing, or by subjecting the cells to a transient osmotic stress immediately after the electrical hemolysis step. An interesting finding is that the breakdown voltage, although constant throughout each normally distributed ghost size distribution, increases with increasing mean volume of the ghost populations.     

Effects of electric field strengths on fusion and in vitro development of domestic cat embryos derived by somatic cell nuclear transfer

The present study was conducted to determine the effect of electric field strength on the rate of membrane fusion between the somatic cell and cytoplast and on subsequent in vitro development of reconstructed embryos. Additionally, the in vitro developmental competence of cat oocytes artificially activated after 44 h of maturation culture was examined. An efficient fusion rate (64.2%) was obtained by applying a single pulse of 1.5 kV/cm for 50 micros, and the fusion rate remained almost constant at the higher field intensity (59.8 and 54.9% at 1.7 and 2.0 kV/cm, respectively). Although the cleavage rate of fused embryos increased with an increase of the electric field strength, there were no differences among the groups with respect to the proportion of development to the morula and blastocyst stages. In the additional experiment, oocytes at the metaphase II stage after culture for 44 h were activated by the combination of calcium ionophore (CaI) with cycloheximide (CHX). Some (11.8%) of activated oocytes developed to the blastocyst stage. Results from this study indicated that electric field strength affects the rates of fusion and cleavage but has no significant effects on the development to the blastocyst stage of reconstructed embryos. Prolonged maturation culture of cat oocytes (up to 44 h) decreased their ability to develop to the blastocyst stage.     

高压静电场对绵羊精子存活率的影响

采用不同剂量的高压静电场处理绵羊精液,经分析发现,高压静电场对绵羊精具有激活作用。能提高绵羊精液品质,表现在适当剂量的高压静电场能显著地提高绵羊精子存活率,其中以６００ｋＶ／ｍ剂量处理效果最佳。１００ｋＶ／ｍ和３００ｋＶ／ｍ剂量对精子刺激不足,而９００ｋＶ／ｍ剂量则对精子刺激过程,导致部分精子损伤和死亡,同样达不到预期的效果。     

Electrical hemolysis of human and bovine red blood cells

Summary The external electric field strength required for electrical hemolysis of human red blood cells depends sensitively on the composition of the external medium. In isotonic NaCl und KCl solutions the onset of electrical hemolysis is observed at 4 kV per cm and 50% hemolysis at 6 kV per cm, whereas increasing concentrations of phosphate, sulphate, sucrose, inulin and EDTA shift the onset and the 50% hemolysis-value to higher field strengths. The most pronounced effect is observed for inulin and EDTA. In the presence of these substances the threshold value of the electric field strength is shifted to 14 kV per cm. This is in contrast to the dielectric breakdown voltage of human red blood cells which is unaltered by these substances and was measured to be 1 V corresponding in the electrolytical discharge chamber to an external electric field strength of 2 to 3 kV per cm. On the other hand, dielectric breakdown of bovine red blood cell membranes occurs in NaCl solution at 4 to 5 kV per cm and is coupled directly with hemoglobin release. The electrical hemolysis of cells of this species is unaffected by the above substances with exception of inulin. Inulin suppressed the electrical hemolysis up to 15 kV per cm. The data can be explained by the assumption that the reflection coefficients of the membranes of these two species to bivalent anions and uncharged molecules are field-dependent to a different extent. This explanation implies that electrical hemolysis is a secondary process of osmotic nature induced by the reversible permeability change of the membrane (dielectric breakdown) in response to an electric field. This view is supported by the observation that the mean volumes of ghost cells obtained by electrical hemolysis can be changed by changing the external phosphate concentration during hemolysis and resealing, or by subjecting the cells to a transient osmotic stress immediately after the electrical hemolysis step. An interesting finding is that the breakdown voltage, although constant throughout each normally distributed ghost size distribution, increases with increasing mean volume of the ghost populations.     

The effect of moving air on detection of a 60-Hz electric field

Two potential mechanisms in detection of a 60-Hz electric field by albino rats were examined: field-induced movement of the vibrissae and field-induced vibration of the skin. Specifically, the experiment tested field detection in a moving stream of air designed to mask field-induced movement of the skin, fur, and vibrissae. Rats were trained to detect electric fields and were then tested at field intensities from 0–25 kV/m rms. As previously reported, rats demonstrate unmistakable behavioral evidence of field detection at all intensities above 7.5 kV/m. After establishing detection in still air, field detection was re-examined in moving air (average air velocity approximately 2.8–6.8 m/s). The primary result is that the wind produced no change in detection at field intensities above threshold (> 7.5 kV/m). Indeed, at these intensities detection was virtually identical in still and moving air. A secondary finding is that moving air produced statistically significant (P < .05) but apparently contradictory effects on detection when the field intensity was below threshold. On no-field trials the wind lowered scores (i.e., fewer presses on the field-off lever); however, on subthreshold field trials, the wind actually increased detection scores (i.e., more presses on the field-on lever). While this no-field and subthreshold field result is interesting and deserves further study, we place primary emphasis on the finding that, if the field was detectable in still air, it was also detectable in moving air. This result leads us to believe that movement of the vibrissae, fur, or skin is not likely to be the main mechanism of electric-field detection in our subjects. © 1993 Wiley-Liss. Inc.     

Endocrinological effects of strong 60-Hz electric fields on rats

Adult male rats were exposed or sham-exposed to 60-Hz electric fields without spark discharges, ozone, or significant levels of other secondary variables. No effects were observed on body weights or plasma hormone levels after 30 days of exposure at an effective field strength of 68 kV/m. After 120 days of exposure (effective field strength = 64 kV/m), effects were inconsistent, with significant reductions in body weight and plasma levels of follicle-stimulating hormone and corticosterone occurring in one replicate experiment but not in the other. Plasma testosterone levels were significantly reduced after 120 days of exposure in one experiment, with a similar but not statistically significant reduction in a replicate experiment. Weanling rats, exposed or sham-exposed in electric fields with an effective field strength of 80 kV/m from 20 to 56 days of age, exhibited identical or closely similar growth trends in body and organ weights. Hormone levels in exposed and sham-exposed groups were also similar. However, there was an apparent phase shift between the two groups in the cyclic variations of concentrations of hormones at different stages of development, particularly with respect to follicle-stimulating hormone and corticosterone. We concluded that 60-Hz electric fields may bring about subtle changes in the endocrine system of rats, and that these changes may be related to alterations in episodic rhythms.     

Perception and the Characteristics of the Response of Honey Bees,Paper Wasps,and Red Wood Ants to a Low-Frequency Electric Field

Bees, wasps, and ants have no specialized receptors for the perception of an electric field. An appropriate response to naturally occurring electric fields in bees and ants is associated with atmospheric exposure, amplified by the approach of the front of a thunderstorm. The primary transducers of mechanoreceptors that respond to displacement are related to the perception of low-frequency electric fields of high intensity by insects. The non-specific mechanism of perception of electric fields is based on irritation by induced currents that flow in the locations of their contact with each other and/or conductive surfaces. The frequency dependence of the electric field sensitivity is determined mainly by the magnitude of the current induced by it and the intensity of its contact action. The magnitude of the current induced in the outer part of the insect body is non-linearly related to the frequency of the electric field. The region with the highest sensitivity to electric fields is close to 500 Hz, which is consistent with the maximum magnitude of the induced current. At the same time, the threshold of the sensitivity to an electric field in wasps is approximately 0.04 kV/m, while in bees it is 0.45 kV/m. Ants react to the action of an electric field of 7–10 kV/m by slowing their movement. Magnetic fields and ionization, which accompany the generation of an electric field whose intensity reaches 15–20 kV/m, do not stimulate changes in the behavior of insects.

     

Power-frequency electric fields averaged over the body surfaces of grounded humans and animals

Calculated electric-field strengths averaged over the body surfaces of grounded humans, swine, rats, horses, and cattle exposed to vertical, uniform, power-frequency electric fields are presented. To produce the same average fields over the body surfaces of grounded animals, as that experienced by a grounded man exposed to an unperturbed vertical field of 10 kV/m, the following unperturbed fields are required: swine, 19 kV/m; rat, 37 kV/m; horse, 18 kV/m; cow, 18 kV/m.     

Electroacoustic fusion of millilitre volumes of cells in physiological medium

A technique is described in which erythrocytes suspended in 1.1 ml of 145 mM NaCl, have been fused by electrofusion. The cells in suspension were brought into close contact by setting up a 3 MHz ultrasonic standing wave in a cylindrical cell container. The aluminium foil base of the container served both to transmit ultrasound and as an electrode for electrofusion. The electric pulse was generated by a capacitor discharge system. The electric field strength required to fuse cells increased as the ionic strength of the cell suspending phase increased. Cells in physiological saline fused at an electric field strength of 7.3 kV/cm with a 50 microseconds pulse.     

土壤表面电场对黑土团聚体破碎和侵蚀的影响

通过定量调控土粒表面电场强度,采用湿筛法和模拟降雨试验,研究了土壤表面电场对东北黑土团聚体稳定性和土壤侵蚀的影响。结果表明: 1)随着土壤本体溶液电解质浓度的降低,土壤颗粒表面电位绝对值和电场强度均不断增加,宾县黑土和克山黑土表面电场强度均可达10⁸ V·m^-1数量级;2)随着土粒表面电场增强,土壤团聚体的破碎程度增大,平均重量直径表现为先急剧减小而后保持不变;3)通过人工模拟降雨试验可知,随本体溶液电解质浓度降低,颗粒表面电场增强,土壤流失强度增大。当电解质浓度＜0.01 mol·L^-1,对应宾县黑土和克山黑土的表面电位绝对值分别大于210和209 mV时,土壤累积流失量随时间的分布曲线较为接近,表明0.01 mol·L^-1是影响土壤侵蚀强度的电解质临界浓度值;4)土壤累积流失量与团聚体平均重量直径之间表现出良好的线性关系。综上,当雨水进入土壤,土粒表面电场增强,引发土壤团聚体破碎并释放大量细颗粒,最后在雨水冲刷作用下发生侵蚀。该研究结果可为深入理解东北黑土区土壤水蚀机理提供新的思路。