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PubMed1958

Electrical activity in the chemoreceptors of the blowfly. II. Responses to electrical stimulation.

An analysis of the various parts of the electrical responses to the chemical and electrical stimulation of a single labellar chemosensory hair of the blowfly, Phormia regina, indicates that the recording conditions for the spike potentials approximate the intracellular recordings made in other types of sense cells. The large positive resting potential probably arises from the basement membrane of the hypodermal cells and neurilemma rather than from the neurons at the base of the chemosensory hair. The responses to polarizing currents passed through single chemosensory hairs support this analysis. The behavioral responses to similar polarizing currents are shown to result from the action of the current on the neurons at the bases of the adjacent chemosensory hairs. The reported neural interaction of the two chemosensory neurons associated with the chemosensory hair is probably due to the physical-chemical attributes of the stimulating solution rather than to any real neural interaction. Observations on the latency of the initial nerve impulse in response to chemical stimulation indicate that the chemosensory neurons are normally free from spontaneous spike activity.

Action Potentials↗
PubMed1992

Electrical impedance tomography. The provision of an electric field of controllable penetration into a cylinder.

If a cylinder carries on its surface an electric charge of a density which is constant in the axial direction, but which varies sinusoidally with an integral number of wavelengths around the circumference, then inside the cylinder the electric field has its maximum value at points adjacent to the surface, and reduces continuously as the axis is approached. The rate of reduction increases with the number of wavelengths. A rotating cylinder of such charge may be simulated by a number (divisable by three) of equally spaced conducting bars mounted longitudinally on the surface of a stationary cylinder, the bars being connected in sequence to the lines of a three-phase voltage supply. The number of wavelengths of charge around the circumference can be varied by the connection together of a chosen number of adjacent bars effectively to form a single bar, and so fields of varying penetration depths can be produced from a fixed frequency supply. The variation of the resulting currents would be related to the corresponding variation in the complex conductivity of the cylinder material.

Electric Conductivity↗
PubMed1998

Phospholipid translocation from the outer to the inner leaflet of synaptic vesicle membranes isolated from the electric organ of Japanese electric ray Narke japonica.

The phospholipid translocation from the outer to the inner leaflet of synaptic vesicles isolated from the electric organ of the Japanese electric ray, Narke japonica, was measured using fluorescent phospholipid probes. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), or phosphatidylserine (PS) with a fluorescent NBD-labeled short acyl chain at the sn-2 position was mixed with purified synaptic vesicles and the probe in the outer leaflet of the membranes was reduced with dithionite to quench the fluorescence from time to time. The percentage of fluorescence remaining after the dithionite treatment served as an index for the phospholipid translocation. The results obtained indicated that about 30, 13, and 9% of NBD-PE, NBD-PS, and NBD-PC, respectively, were translocated from the outer to the inner leaflet in 3 h. Thus, the translocation activity in synaptic vesicle membranes was much higher for PE than for PS, in contrast to the previous results obtained with plasma membranes, including synaptosomal membranes. The percentages of the phospholipid in the inner leaflet at equilibrium were estimated to be 41, 31, and 14% for PE, PS, and PC, respectively. The translocation was inhibited by pretreatment with an SH reagent, iodoacetamide, indicating the involvement of a proteinaceous translocator. These data may provide a biochemical basis for elucidating the mechanisms of membrane fusion and exocytosis at nerve endings.

4-Chloro-7-nitrobenzofurazan↗
PubMedDate not supplied

The immediate effectiveness of electrical nerve stimulation and electrical muscle stimulation on myofascial trigger points.

This study is designed to investigate the immediate effectiveness of electrotherapy on myofascial trigger points of upper trapezius muscle. Sixty patients (25 males and 35 females) who had myofascial trigger points in one side of the upper trapezius muscles were studied. The involved upper trapezius muscles were treated with three different methods according to a random assignment: group A muscles (n = 18) were given placebo treatment (control group); group B muscles (n = 20) were treated with electrical nerve stimulation (ENS) therapy; and group C muscles (n = 22) were given electrical muscle stimulation (EMS) therapy. The effectiveness of treatment was assessed by conducting three measurements on each muscle before and immediately after treatment: subjective pain intensity [(PI) with a visual analog scale], pressure pain threshold [(PT) with algometry], and range of motion [(ROM) with a goniometer] of upper trapezius muscle (lateral bending of cervical spine to the opposite side). When the effectiveness of treatment was compared with that of the placebo group (group A), there was significant improvement in PI and PT in group B (P < 0.01) but not in group C (P > 0.05). The improvement of ROM was significantly more in group C (P < 0.01) as compared with that in group A or group B. When each group was divided into two additional subgroups based on the initial PI, it was found that ENS could reduce PI and increase PT significantly (P < 0.05), but did not significantly (P > 0.05) improve ROM, as compared with the placebo group for both subgroups. EMS could significantly (P < 0.05) improve ROM, but not PT, better than the placebo groups, for either subgroup. It could reduce PI significantly more (P < 0.05) than placebo controls only for the subgroup with mild to moderate pain, but not with severe pain. For pain relief, ENS was significantly better (P < 0.05) than EMS; but for the improvement of ROM, EMS was significantly better (P < 0.05) than ENS. It is concluded that ENS is more effective for immediate relief of myofascial trigger point pain than EMS, and EMS has a better effect on immediate release of muscle tightness than ENS.

Adult↗
PubMed2001

Outcome of out-of-hospital postcountershock asystole and pulseless electrical activity versus primary asystole and pulseless electrical activity.

OBJECTIVE: In the prehospital setting, countershock terminates ventricular fibrillation (VF) in about 80% of cases. However, countershock is most commonly followed by asystole or pulseless electrical activity (PEA). The consequences of such a countershock outcome have not been well studied. The purpose of this investigation was to compare the outcome of prehospital VF victims shocked into asystole or PEA with that of patients whose first documented rhythm was asystole or PEA (primary asystole or PEA). DESIGN: Observational, retrospective study conducted over 5 yrs (1995-1999). SETTING: A municipal hospital with a catchment area of >200,000. PATIENTS: Consecutive adult patients with out-of-hospital nontraumatic cardiopulmonary arrest of cardiac origin. Patients found in VF who developed asystole or PEA after countershocks (group 1) and patients found in asystole or PEA (primary asystole or PEA) (group 2) were included if the reported downtime was <10 min. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Study end points included restoration of circulation (defined as a pulse for any duration), survival to hospital admission, and survival to hospital discharge. Ratios were determined, 95% confidence intervals were calculated, and observed differences were compared. For group 1 patients (n = 101), 61% of patients had a bystander-witnessed collapse and 34% received bystander cardiopulmonary resuscitation. For group 2 patients (n = 140), collapse was bystander witnessed in 71% and 45% received bystander cardiopulmonary resuscitation. These differences were not statistically significant. Restoration of circulation was significantly more frequent in group 2 than group 1 (42% vs. 16%, p <.001) as was survival to hospital admission (36% vs. 11%, p =.001). Survival to hospital discharge was greater in group 2 patients, but the difference failed to achieve statistical significance (10% vs. 3%, p =.062). CONCLUSIONS: Countershock of prolonged VF followed by a nonperfusing rhythm has a worse prognosis than primary asystole or PEA and may be related to myocardial electrical injury.

Adult↗
PubMed2000

Second-order model of membrane electric field induced by alternating external electric fields.

With biological cells exposed to ac electric fields below 100 kHz, external field is amplified in the cell membrane by a factor of several thousands (low-frequency plateau), while above 100 kHz, this amplification gradually decreases with frequency. Below 10 MHz, this situation is well described by the established first-order theory which treats the cytoplasm and the external medium as pure conductors. At higher frequencies, capacitive properties of the cytoplasm and the external medium become increasingly important and thus must be accounted for. This leads to a broader, second-order model, which is treated in detail in this paper. Unlike the first-order model, this model shows that above 10 MHz, the membrane field amplification stops decreasing and levels off again in the range of tens (high-frequency plateau). Existence of the high-frequency plateau could have an important impact on present theories of high-frequency electric fields effects on cells and their membranes.

Biomedical Engineering↗
PubMed1995

Effect of electrical stimulation on gastric electrical activity, motility and emptying.

The aim was to measure the effect of gastric electrical stimulation on the frequency of canine antral pacesetter potentials (PPs), the strength of antral contractions, and the rate of gastric emptying while fasting, after feeding and with pentagastrin stimulation. Four conscious dogs with a stimulating electrode placed 10 cm proximal to the pylorus and recording electrodes and strain gauges placed 7, 5 and 3 cm proximal to the pylorus underwent myoelectric and strain gauge recordings while fasting, after feeding (250 ml 5% dextrose labelled with polyethylene glycol), and during pentagastrin infusion (0.5 micrograms kg-1 min-1) on four separate days. On each day, electrical stimulation was done using one of four stimulation frequencies (0, 6, 30 and 1200 stimuli per minute [s.p.m.]). Stimulation at 6 and 30 s.p.m. increased the fasting and fed PP frequency, whereas 1200 s.p.m. stimulation did not. Feeding decreased the maximum driven frequency, and pentagastrin increased it. Neither the motility index nor the gastric emptying rate were consistently changed by stimulation at any frequency. In conclusion, canine proximal antral stimulation at 6 and 30 s.p.m. sped PP frequency during fasting and after feeding, but stimulation over a wide range of frequencies had little effect on gastric contractions and emptying.

Animals↗
PubMed1998

Passive electrical properties of ventral horn neurons in rat spinal cord slices.

Recordings were made from large neurons located in the ventral horn of transverse spinal cord slices from young rats (7-15 days). Whole cell recordings were made simultaneously with two electrodes from the soma of these neurons, visualized using infra-red differential interference contrast optics. Positive identification of motoneurons could not always be achieved. The response of a neuron to a brief pulse of current delivered by one electrode, and recorded by the other electrode, were matched optimally to responses of a compartmental model of the same neuron with an identical current pulse as input. The compartmental model was based on a reconstruction of the neuron, using Biocytin staining. The compartmental model had three free parameters: specific membrane capacitance (Cm), membrane resistivity (Rm), and cytoplasmatic resistivity (Ri), all assumed to be uniform throughout the neuron. The experimental and model responses could be matched unequivocally for four neurons, giving Cm = 2.4 +/- 0.5 microF/cm2, Rm = 5.3 +/- 0. 9 kOmega/cm2, and Ri = 87 +/- 22 Omega/cm. No somatic shunt was required. For the remaining six neurons, a less perfect fit (but still within 95% confidence limits) was indicative of nonhomogeneous membrane properties. The electrotonic length of uncut dendrites was 0.85 +/- 0.14 lambda. The results resolve the issue of a somatic shunt conductance for motoneurons, relegating it to a microelectrode impalement artifact. They are consistent with previous reports on the electrical compactness of motoneurons to steady state currents and voltages. However, the much higher value of Cm (than the previously assumed 1 microF/cm2) implies much greater dendritic attenuation of fast synaptic potentials, and a much enhanced integrative response of motoneurons to synaptic potentials.

Action Potentials↗
PubMed1986

Electrical responses of the smooth muscle of the guinea-pig cerebral artery to brief electrical stimulation.

Electrical responses to brief electrical stimulation were investigated in the cerebral artery of a guinea-pig using a microelectrode. A single brief stimulus (0.05 ms) induced a spike potential followed by a depolarizing slow-potential, and these events were associated with muscle contraction. An outward current injected into the smooth muscle cell induced spike potential but failed to induce depolarizing slow-potential. These activities persisted in the presence of TTX (10(-6) M), guanethidine (5 X 10(-6) M), or atropin (10(-5) M). TEA (5 mM) enhanced the amplitude of the spike potential, but not that of the depolarizing slow-potential. When the external Na was reduced, the membrane transiently hyperpolarized. During this period, the depolarizing slow-potential could be evoked. In a Cl-deficient solution, the membrane depolarized and the amplitude of the depolarizing slow-potential decreased. From these observations it is believed that the contribution of K, Na, or Cl is minor. In a 20 mM-Ca solution, a brief stimulation induced neither spike potential nor depolarizing slow-potential, but did induce a hyperpolarizing slow-potential. The hyperpolarizing slow-potential was also induced in a Na-deficient solution, but only after completion of Na re-distribution across the membrane. These observations suggest that a substance released by brief stimulation produces a prolonged change in ionic conductances of the smooth muscle membrane, allowing the muscle to contract for a certain period.

Animals↗
PubMed1990

Effect of electric field on erythrocyte sedimentation rate. II. Dependence on electric current.

We measured the electric current dependence of sedimentation curves of swine erythrocytes in a saline solution at the volume fraction of erythrocytes H = 0.091 and 0.220. The sedimentation curve fitted well to the exponential type equation l = a[1-exp(-bt)] at the upward initial electric current I0 = 0.50 mA, 1.01 mA and 1.50 mA, where l is the length of the medium layer at time t, and a and b are phenomenological parameters. The initial slope v0 of sedimentation curve was enhanced from 0.68 mm/hr at I0 = 0 mA to 2.85 mm/hr, 3.87 mm/hr and 5.50 mm/hr at I0 = 0.50 mA, 1.01 mA and 1.50 mA, respectively, for H = 0.220. We also made sedimentation measurements of erythrocytes in their own plasma at H = 0.220 and 0.316. Sedimentation curves coincided with the sigmoidal type equation l = l infinity/[1 + (t50/t)beta] at I0 = 0 mA and 0.50 mA, where l infinity is l at t----infinity, t50 is the time when the plasma level falls to l infinity/2 and beta is a constant. The maximum slope vmax of sedimentation curve increased from 13.29 mm/hr at I0 = 0 mA to 18.65 mm/hr at I0 = 0.50 mA for H = 0.220.

Animals↗
PubMed1986

Comparison of the effects of leaving needle, direct current electrical acupuncture, and low-frequency electrical acupuncture therapy.

During a 3 year period from 1978 to 1980, one hundred and seventeen patients who came to the Pain Clinic of the Department of Anesthesiology of the Osaka Medical College complaining of pain, were treated with leaving needle(LN), direct current electrical acupuncture (EAP), or low-frequency electrical acupuncture(LFEA). The immediate effects of these therapies were investigated in a period of 3 days after treatment, on the basis of the patient's subjective evaluation of his relief from pain on a scale of 10 before treatment. Appearance patterns of therapeutic effects of these therapies were divided into four types: persistent (therapeutic effects persist during the 3 day period immediately after treatment), downward (therapeutic effects gradually decrease immediately after treatment), upward (therapeutic effects gradually appear after treatment), and unaltered (therapeutic effects were fair or poor during the 3 days after treatment). In addition, it was seen that of the three therapies LFEA was the best one in producing a persistent therapeutic effect and a good rate of effectiveness in the first day immediately after treatment.

Acupuncture Therapy↗
PubMedDate not supplied

[Changes in the electrical properties of atrial trabecula induced by an electric stimulus].

Electrical activity, excitation threshold and "steady--state" current-voltage, relationship (estimated under voltage clamp conditions) in the membrane of chicken embryo atrial trabecula were investigated by means of double succrose-gap technique. Application of short (10 msec) electrical stimuli with magnitudes up to 6.10(-5) a (1-150 threshold) resulted in increased excitability and appearance of spontaneous activity. Release of neurotransmitters and polarity of the applied sitmulus are shown not to play a significant role in the changes in membrane excitability observed, the main cause of the latter being the increased sodium permeability of the membrane.

Animals↗
PubMedDate not supplied

[Study of the orientation of DNA molecules in an electrical field by anisotropy of electrical conductivity of their aqueous solution].

Electro-conductive anisotropy of DNA solution caused by the molecular orientation in the external electric field was investigated. The dependence of a relative change of the conductivity of aqueous-salt DNA solution on the electric field in the amplitude range 0-700 V/cm and in the frequency range 100 Hz-10 kHz was studied. It was pointed out that the field thermal effect is an overcoming factor when the orientation of DNA molecules is investigated by field-free relaxation.

DNA↗
PubMed1990

[Physical and biophysical aspects of high-energy intracardiac electric discharges. III. Correlation between physical and electric effects for the use of supraliminal shocks].

Using the same methods as for the measurement of electrical parameters by means of an oscilloscope with a wave shape calculator to determine at all points the energy and impedance values, as well as high speed cinematography, the analysis of the behavior of these parameters for shocks with energies close to those used in clinical medicine can be carried out. It shows namely an important decrease in the impedance at the current peak due to an important ionization of the fulguration bubble. It underlines the different behavior of the anode and cathode bubbles, in relation with the size of the bubbles obtained thanks to rapid cinematography. Comparative measurements concerning the polarity, the size of the indifferent electrode, the medium used in vitro and in vivo have supplied the elements to enable the precise determination of the adequate electrical parameters for the good use of fulguration.

Animals↗
PubMed1989

[Magneto-electrical stimulation (MES)--compared with percutaneous electrical stimulation (PES)].

The central motor conduction was studied in 30 normal volunteers using a recently developed magneto-electrical stimulation technique (MES). The results were compared with those obtained by percutaneous electrical stimulation technique (PES) described previously. We made a magnetic stimulator similar to that of Barker et al. To stimulate the motor cortex, the magnetic coil was placed over the head. It was placed over the seventh cervical spinous process (C7) for cervical stimulation, and the first lumbar spinous process (L1) for lumbar stimulation. Cortical stimulation was performed when the subjects were at rest, and also at during weak voluntary contraction in some of them. Recordings were made from the deltoid (Del), biceps brachii (Bi), extensor carpi radialis (ECR), thenar, quadriceps femoris (Quad), tibialis anterior (TA) and flexor hallucis brevis (FHB) muscles with a pair of surface electrodes. The cortical and spinal latent periods (Lcor and Lsp, respectively) were measured. The central conduction time (CCT) was obtained by subtracting Lsp from Lcor for each muscle. In all subjects, responses were readily obtained by cortical, cervical and lumbar stimulations without discomfort in all the muscles examined. The cortical responses with amplitudes of more than 1mV could be recorded even in the lower limb muscles. There were no significant differences in Lsp and CCT between MES and PES, in all the upper limb muscles examined. The Lcors of the lower limb muscles obtained by MES were not different from those obtained by PES. However, the Lsps obtained by MES were significantly shorter than those by PES in the Quad and TA muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1977

The effect of intravaginal electrical stimulation on the feline urethra and urinary bladder. Electrical parameters.

Intravaginal electrical stimulation (IVS) in cats caused urethral closure and bladder inhibition. The aim was to ascertain the electrical parameters most appropriate for these effects. Minimum voltage was used as main criterion to select an effective, non-destructive stimulation when the shape, frequency and duration of the pulses were systematically varied. Urethral closure was achieved at minimum voltage (3 V) with alternating pulses at a frequency of 50 Hz and a pulse duration of 1.5 ms. Corresponding optimal parameters for bladder inhibition were: alternating pulses, 10 Hz and 1.5 ms. Minimum voltage was 1 V. Moreover, the positions of the electrodes were of significance for the responses. The clinical implications of these findings are that: 1)more differentiated treatment of incontinence could be achieved by adapting the stimulation parameters to the cause of incontinence, and 2) specific electrode positions would probably give optimal responses.

Animals↗
PubMed1983

Epidermal changes in heat and electrically injured pig skin. A light microscopic study of the influence of heat energy intensity and electrical current frequency.

Pigs were exposed to heat of low and high temperature and electricity of various frequences. Comparable amounts of energy were transferred in all experiments. In lesions induced by heat of low temperature granularity and/or fibrillarity of the cytoplasm were present in the epidermal cells. Lesions induced by heat of high temperature had a similar appearance, but occasionally "white necrosis", defects in the epithelium and light yellow material in stratum corneum were present. Lesions induced by 100.000 hz alternating current were segmental but otherwise microscopically often indistinguishable from lesions produced via transfer of heat of low temperature. Lesions induced by 8000 hz and 59 hz alternating current were segmental. Vesicular nuclei, "white necrosis" and yellow, clumped keratin were present in most lesions. Anode areas in direct current induced lesions showed a shrunken epidermis. The cytoplasm of the epidermal cells were often eosinophilic and homogeneous, and the nuclei were small with condensed chromatin. Occasionally, "empty" nuclei were noted. Yellow, clumped keratin was presented in all lesions. In cathode areas epidermis was of varying thickness and "white necrosis" and vesicular nuclei were present. The pathogenesis of the individual morphological features is discussed based upon theoretical concepts and the difference in morphology of the various lesions encountered in the present study as well as in other studies in this series of experiments. It is concluded that except for lesions produced via transfer of high frequency alternating current the morphology of electrical lesions is specific. Further, an alleged torture instrument was able to produce lesions similar to those observed in the experimental studies.

Animals↗