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PubMedDate not supplied

Auditory brainstem potentials in man evoked by electrical stimulation of the round window.

In normal subjects, round-window electrical stimulation provides a sound sensation and supplies brainstem-evoked responses whose form is just the same of those evoked by sound stimulation. This electrical stimulation also provides a sound sensation in more than 90% of cases of total deafness, which means that at least a few auditory nerve fibres are still present. Thus, this test is indispensable when considering surgical rehabilitation with a multichannel cochlear implant. The diagram of this response to an electrical stimulus differs completely in the case of total deafness and in normal subjects. The correlation between the form of these diagrams and the supposed etiology of the deafness is not significant.

Acoustic Stimulation↗

PubMed2006

Effects of external electrical stimulation on laser-beam-induced experimental thrombosis.

External electrical stimulation (EES) has demonstrated venous antithrombotic properties. The aim of this investigation was to study its antithrombotic properties using unfractionated heparin (UFH) as a reference in arterial and venous mesenteric microvessels. For this purpose a rat model of laser-beam-induced thrombosis was used. Four groups of rats were investigated (n = 7): control, UFH (5 mg /kg), UFH (2.5 mg/kg) and electrical stimulation [e-vascular, E = 10, alternate polarity, in two protocols: (i) 30 min before and during thrombosis induction and (ii) only 30 min before thrombosis induction as preventive stimulation]. This effect was tested in arterial and venous microvessels in the four groups using the continuous protocol and only in arterial microvessels using the preventive protocol. Three parameters were studied: the number of laser beams needed to induce platelet thrombus formation, the number of emboli and the duration of embolization. Induced hemorrhagic time (IHT), platelet aggregation induced by ADP and coagulation tests (activated partial thromboplastin time, aPTT, prothrombin time, pTT, and fibrinogen level) were also determined. Continuous electrical stimulation decreased the number of emboli and the duration of embolization both in arterioles and in venules. It also significantly reduced the amplitude and velocity of the ex vivo platelet aggregation induced by ADP. Contrary to UFH, neither aPTT nor pTT were affected in platelet-poor plasma collected after the induction of thrombosis by laser beam, nor did it modify IHT. Preventive electrical stimulation produced similar results with fewer effects on induced venous thrombosis. These data suggest that EES has a potent antithrombotic effect on arterial and venous thrombosis without any hemorrhagic adverse effects, making it a very promising tool in the prevention and treatment of venous and arterial thromboembolic complications.

Animals↗

PubMedDate not supplied

Electrical stimulation of the ear: clinical applications.

Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the round window. With positive currents, suppression of tinnitus could be induced. With negative currents, auditory sensations were evoked. Since electrical stimulation with DC currents may be hazardous in the long term, it cannot yet be proposed for the suppression of tinnitus. However, electrically evoked hearing sensations with AC currents seem to be of definite interest for some totally deaf patients.

Deafness↗

PubMed2003

Effects of electrical stimulation and insulin on Na+-K+-ATPase ([3H]ouabain binding) in rat skeletal muscle.

Exercise has been reported to increase the Na+-K+-ATPase (Na+-K+ pump) alpha2 isoform in the plasma membrane 1.2- to 1.9-fold, purportedly reflecting Na+-K+ pump translocation from an undefined intracellular pool. We examined whether Na+-K+ pump stimulation, elicited by muscle contraction or insulin, increases the plasma membrane Na+-K+ pump content ([3H]ouabain binding) in muscles from young rats. Stimulation of isolated soleus muscle for 10 s at 120 Hz caused a rapid rise in intracellular Na+ content, followed by an 18-fold increase in the Na+ re-extrusion rate (80 % of theoretical maximum). Muscles frozen immediately or 120 s after 10-120 s stimulation showed 10-22 % decrease in [3H]ouabain binding expressed per gram wet weight, but with no significant change expressed per gram dry weight. In soleus muscles from adult rats, [3H]ouabain binding was unaltered after 10 s stimulation at 120 Hz. Extensor digitorum longus (EDL) muscles stimulated for 10-60 s at 120 Hz showed no significant change in [3H]ouabain binding. Insulin (100 mU ml-1) decreased intracellular Na+ content by 27 % and increased 86Rb uptake by 23 % soleus muscles, but [3H]ouabain binding was unchanged. After stimulation for 30 s at 60 Hz soleus muscle showed a 30% decrease in intracellular Na+ content, demonstrating increased Na+-K+ pump activity, but [3H]ouabain binding measured 5 to 120 min after stimulation was unchanged. Stimulation of soleus or EDL muscles for 120-240 min at 1 Hz (continuously) or 10 Hz (intermittently) produced no change in [3H]ouabain binding per gram dry weight. In conclusion, the stimulating effects of electrical stimulation or insulin on active Na+, K+-transport in rat skeletal muscle could not be even partially accounted for by an acute increase in the content of functional Na+ -K+ pumps in the plasma membrane.

Animals↗

PubMed1991

Transcutaneous magnetic and electrical stimulation over the cervical spine: excitation of plexus roots-rather than spinal roots.

Percutaneous magnetic stimulation (MagStim) and electrical stimulation (ElStim) over the cervical spine were performed in 65 subjects. Compound muscle action potentials (CMAPs) from the abductor digiti minimi (ADM) and the biceps muscles (BICEPS) could be recorded in all subjects tested with both, ElStim and MagStim. Maximal stimulation as determined from the amplitudes of CMAPs was possible in most cases with ElStim but not with MagStim. Latencies after MagStim (centered over C7) and ElStim (cathode over C7/T1, anode positioned 6 cm cephalad in the midline) were not statistically significantly different (P = 0.3). However, in the individual case, it was difficult to predict the precise site at which the motor roots would be activated, since latencies of CMAPs to ElStim and MagStim could differ by up to 1.2 msec. In addition, the excitation site migrated distally when the stimulation intensity was increased with the aim to obtain CMAPs of nearly maximal amplitudes. The results of studying brachial plexus stimulation as well in 22 of the subjects led us to the conclusion that excitation of the motor roots occurs on the average 7 cm (range: 1.4-8.2 cm) proximally to Erb's point. This was confirmed by the finding that when the C7 motor root was stimulated directly intraoperatively within the intervertebral foramen, the excitation site was calculated to be 7.7 cm distal to the foramen and 8.4 cm proximal to Erb's point.

Action Potentials↗

PubMed2002

Electrical stimulation enhances the survival of axotomized retinal ganglion cells in vivo.

In view of recent reports on the survival promotion of damaged spiral ganglion cells and motoneurons by electrical stimulation, we hypothesized that an electrical stimulation of the cut optic nerve (ON) may promote the survival of axotomized retinal ganglion cells (RGCs) in vivo. To test this hypothesis, we examined 1 week after ON transection the RGC densities in the retinas with or without electrical stimulation. The densities of surviving RGCs in the retinas with the electrical stimulation increased as compared with those without the electrical stimulation. We concluded that electrical stimulation of the ON enhances the survival of axotomized RGCs in vivo, probably due to electrical activation of their soma.

Animals↗

PubMed1996

[A study on the change of myocardial neuropeptide Y release induced by electric stimulation and myocardial ischemia in guinea pig heart].

Electrical stimulation of the left stellate ganglion in guinea pig heart evoked a calcium-dependent, exocytotic release of neuropeptide Y (NPY). Stimulation after 10 min of global ischemia (S2), compared with control period stimulation (S1), had no significant effect on the NPY release. The release of NPY produced by the same stimulation after 20 min of ischemia was inhibited to certain extent (S2/S1: 0.72, P < 0.05), whereas the inhibition of NPY release disappeared after 5 min of reperfusion (with a S2/S1 of 1.01). Ischemia alone, without electric stimulation, did not apparently induce NPY release, suggesting that electrical stimulation may induce a calcium-dependent, exocytotic release of NPY. It is further suggested that the inhibition of NPY release may be produced by some metabolites and the abolishment of the inhibition after reperfusion may be due to washout of the metabolites.

Animals↗

PubMed1990

Capsaicin-sensitive afferent fibers contribute to gastric mucosal blood flow response to electrical vagal stimulation.

Electrical stimulation of the peripheral vagus produces a noncholinergic increase in gastric mucosal blood flow (GMBF) via unknown mechanisms. The purpose of this study was 1) to investigate whether a portion of the increase in GMBF during prolonged electrical vagal stimulation involves a mechanism separate from augmented acid secretion and 2) to determine whether antidromic activation of afferent fibers contributes to the vascular or secretory responses to electrical vagal stimulation. Electrical vagal stimulation (40 V, 6 Hz, 2 ms) applied for 30 min to the distal cut end of the subdiaphragmatic ventral vagus significantly increased gastric acid secretion and GMBF measured by hydrogen gas clearance. Atropine (0.15 mg/kg iv) or omeprazole (10 mumol/kg iv) completely abolished the secretory response to electrical vagal stimulation, while a significant increase in GMBF remained. Pretreatment with perineural application of the sensory neurotoxin capsaicin to both cervical vagi significantly reduced by 48% the increase in GMBF but not gastric acid secretion; atropine completely abolished the remaining vascular response in capsaicin-treated rats. These results suggest that prolonged electrical vagal stimulation induces a sustained increase in GMBF partially independent of augmented acid secretion and that the noncholinergic portion of the vascular response is mediated by capsaicin-sensitive vagal afferent fibers.

Afferent Pathways↗

PubMedDate not supplied

Transcranial electrical stimulator producing high amplitude pulses and pulse trains.

Transcranial electrical stimulation can be used for clinical investigations of the central nervous system and for monitoring of motor nerve tracts during surgical operations. We wished to reduce the pain involved with the transcranial electrical stimulation and to improve the usefulness of the method for monitoring during surgical operations. A dedicated transcranial electrical stimulator was designed having special features to reduce the pain sensation and the nerve blocking effect of anaesthetics. It provides constant current and constant voltage stimulation pulses with very short duration and high amplitude. The pulse length is adjustable in the range of 15 to 125 microseconds, while the maximum amplitude is 100 V and 1 A for voltage and current stimulation modes, respectively. Special features included high-repetition-rate pulse trains (50-2000 pulses s-1) and a three-electrode stimulation configuration. We suggest that the electrical transcranial stimulation has the potential to be a relatively painless method for routine clinical investigations and a reliable method for monitoring during surgery.

Amplifiers, Electronic↗

PubMed1981

Fixation of porous titanium implants in cortical bone enhanced by electrical stimulation.

The effect of in vivo electrical stimulation on the interfacial strength between porous titanium implants and cortical bone was studied in mongrel dogs. The interfacial shear strength of the stimulated implants was consistently greater than that of controls. No difference could be observed in the quality of bone ingrowth. The data suggest that the rate and quantity of bone ingrowth were enhanced by electrical stimulation.

Animals↗

PubMed1992

Respiration in vitro: II. Electrical stimulation.

The present report describes electrical-stimulation-induced activity recorded from intercostal muscles in the neonatal rat rib-attached, in vitro brain stem-spinal cord preparation. The muscle bursts induced by electrical stimulation included a short-latency twitch contraction and a long-latency modulated contraction similar to that observed during spontaneous respiratory-like activity. Multilevel recordings showed a cephalocaudal order of recruitment of intercostal muscles similar to that observed during spontaneous activity. The optimal parameters of stimulation were 2-msec pulses delivered at 0.1-0.2 Hz. Trains of pulses also were effective. These movements could be induced following stimulation of various sites within each segment of the spinal cord, with the lowest threshold sites located in the ventrolateral funiculus and intermediate gray. Stimulation of every cervical segment was effective in inducing respiratory-like activity, with the lowest-threshold segments being C1, C2, and C5. These results suggest that low-frequency, long-duration pulses applied directly to the spinal cord can induce respiratory-like activity similar to that observed during spontaneous activity in the neonatal rat, rib-attached in vitro brain stem-spinal cord preparation. The ability to elicit a coordinated respiratory pattern even after a high spinal transection suggests that such stimulation may be effective in inducing respiratory-like activity in the absence of descending brain stem connections.

Animals↗

PubMed1984

Respiratory rhythmically regulated electrical stimulation of paralyzed laryngeal muscles.

Electrical stimulation of the posterior cricoarytenoid muscle, synchronized with inspiration, was achieved in dogs, utilizing a radio frequency stimulus triggered by a chest wall expansion transducer. This system brings about the abduction of the paralyzed vocal cord for the entire duration of inspiration, which allows a normal flow of air through the larynx. The stimulation system could be tested successfully in actual experiments in dogs with artificial paralysis of the recurrent laryngeal nerve. Its effectiveness could be proved through observation of the vocal cord movements (photographic documentation) and recording subglottic pressure variations. Transmission of stimulation energy is effected by electrical induction.

Animals↗

PubMed2005

Regional variation in capture of fibrillating swine left ventricle during electrical stimulation.

INTRODUCTION: While it has been shown that electrical stimulation can capture a region of myocardium during ventricular fibrillation (VF), the ideal location to stimulate to maximize capture of the fibrillating in vivo left ventricle (LV) is not known. We previously demonstrated a mean directionality to the propagation of VF wavefronts in swine from posterior to anterior LV. We hypothesized that this directionality of VF wavefronts would affect capture of the LV epicardium while stimulating during VF. METHODS AND RESULTS: In seven open-chest swine, during different VF episodes, electrical stimulation was performed singly or simultaneously from two lines of 26 epicardial electrodes, one on the posterior LV adjacent to the posterior descending coronary artery and another on the anterior LV adjacent to the left anterior descending coronary artery. Mapping was performed between the line of stimulating electrodes with 768 recording electrodes 2-mm apart. The incidence and extent of epicardium captured by stimulation through the lines of stimulating electrodes were determined in the mapped region. Capture occurred during 67% of 78 VF episodes. Capture from the posterior LV line was achieved in 88% of the episodes and from the anterior LV line in 44% of the episodes (P = 0.001). The maximum amount of myocardium captured was also much greater for stimulating from the posterior as compared to the anterior LV line (232 +/- 168 mm(2) vs 64 +/- 124 mm(2), P = 0.003). A significant part of the variability in capture was related to the direction of the mean VF wavefront velocity vector in each animal (r = 0.84, P < 0.05). CONCLUSION: Electrical stimulation from the posterior LV resulted in a greater incidence and extent of LV capture than stimulation from the anterior LV. A significant component of the variability in capture is related to the mean direction of VF wavefronts.

Animals↗

PubMed1975

[Electric stimulation of intestinal motility in the postoperative period].

The authors performed 208 electric stimulations of the bowel motor activity with the aim of prophylaxis and treatment of its postoperative paresis. The studies have shown that electric stimulation accelerated considerably the process of rehabilitation of the bowel motor function, but it would not prevent the development of grave functional intestinal obstruction. But nevertheless electric stimulation is a highly effective method in the complex of measures for treatment of grave functional intestinal obstruction. Electric stimulation of the bowel should be introduced in every day practice of intensive postoperative care departments.

Electric Stimulation↗

PubMed1997

[Does maximum short-term electric stimulation cause contraction of the pelvic floor muscles?].

Electric stimulation is successfully used in the treatment of the stress and urgent type of incontinence. Electric stimulation of the muscles of the pelvic floor causes reflex contraction of the striated peri- and paraurethral muscles and is associated with concurrent reflex inhibition of the detrusor muscle. The therapeutic results depends greatly on the total or at least partially preserved innervation of the muscles of the pelvic floor by the pudendal nerve. One of the possible stimuli of the pelvic floor muscles is maximal electric stimulation (MES) and the objective of our study was to evaluate the effect of MES on the muscles of the pelvic floor or to detect possible changes by US and urodynamic examination. The study comprised women with the stress type of incontinence (GSI). The group was formed by 40 women with GSI, 20 were subjected to US examination and urodynamic examination (n = 20). The group of subjects subjected to urodynamic examination was extended to 40 (n = 40). For electrostimulation a Conmax apparatus was used. The applied frequency was 20 Hz, the amplitude from 0 to 90 mA (grades 0.6), pulse duration 0.75 ms. During the cystometric examination the authors recorded a significant increase of the maximal urethral closure pressure (MUCP), prolongation of the functional (FUL) and anatomical length (AUL) of the urethra during MES. During US examination the authors recorded a significant diminution of the gamma angle, a reduction of the mobility of the UV junction and prolongation of the anatomical length of the urethra during MES. From the investigation ensues that the pelvic floor muscles are contracted during MES and those changes contribute to an increase of the muscular tonus and contracting capacity of the muscles of the pelvic floor and thus cause among other things elevation of the neck of the urinary bladder. The elevation contributes to the normalization of the intraabdominal transmission of pressure to the proximal urethra and thus to treatment of the stress type of urinary incontinence.

Electric Stimulation Therapy↗

PubMed1996

Isolated, electrically-stimulated airway preparations--their use in determining beta-adrenoceptor agonist activity.

We have assessed the suitability of electrically-stimulated superfused preparations of guinea-pig trachea, cat trachea and human bronchus for investigating the relaxant activity of the beta-adrenoceptor agonist, isoprenaline. Superfused strips of guinea-pig trachea, cat trachea and human bronchus all contracted in response to electrical stimulation. Guinea-pig trachea possesses inherent tone, and in its presence, electrical stimulation caused biphasic responses, comprising a modest, transient contraction, usually followed by a longer lasting relaxation. Human bronchus also possesses inherent tone, but responses were variable, generally monophasic, comprising a transient contraction of variable magnitude, but a longer lasting relaxation was occasionally observed after the transient contraction. Cat trachea possesses no inherent tone, and electrical stimulation of this preparation caused simple monophasic contractile responses. On guinea-pig trachea, addition of indomethacin (2.8 microM) abolished the inherent tone, and under these conditions, electrical stimulation caused monophasic contractile responses similar to those observed in cat trachea. On human bronchus, however, indomethacin enhanced inherent tone, which tended to uncover or exaggerate any relaxant component in the responses to electrical stimulation. The 5-lipoxygenase inhibitor, zileuton (10 microM), reduced, but did not abolish, the tone and converted the electrically-induced response to a monophasic contraction. In all preparations in which inherent tone was low or absent, whether naturally (cat trachea) or through pharmacological intervention (guinea-pig trachea with indomethacin, or human bronchus with zileuton), isoprenaline (1-100 nM) inhibited electrically-stimulated contractions in a concentration-related fashion (EC50s: 9-100 nM). In preparations exhibiting inherent tone (guinea-pig trachea with indomethacin or human bronchus with or without indomethacin), this tone was inhibited by isoprenaline. This relaxant activity, on guinea-pig trachea at least, was concentration-related (EC50: 5.4 nM). Such isoprenaline-induced relaxations complicated the analysis of inhibitory effects against electrically-induced contractions. Thus, in such experiments, only at higher concentrations did isoprenaline reliably inhibit these contractions (EC50: 23-119 nM), lower concentrations of isoprenaline often resulting in an apparent enhancement. The enhancement was probably artefactual, resulting from the fact that the electrically-induced contractions originated from a lower baseline. These data suggest that electrically-stimulated airway preparations are suitable for evaluating the relaxant activity of beta-adrenoceptor agonists, but the relaxant potency should be assessed in preparations lacking inherent tone, such as cat trachea, guinea-pig trachea in the presence of cyclo-oxygenase inhibition, or human bronchus in the presence of 5-lipoxygenase inhibition.

Adrenergic beta-2 Receptor Agonists↗

PubMed1988

Electrically stimulated periosteal grafting in the rat.

Osteogenesis of the periosteum was examined in rats. The periosteum electrically stimulated for 6 days was grafted into the axillar muscle, and new bone tissue was found in 40 out of 44 animals (90.9%). Periosteum without stimulation and that with only 2 days of electrical stimulation did not generate new bone tissue. The periosteum electrically stimulated for 4 days did not show substantial new bone formation in the muscle. The periosteal tissue which was initially electrically stimulated for 6 days was definitely transformed into new bone tissue in the muscle. This shows that boneless bone grafting can be accomplished successfully in rats by electrically stimulating the periosteum before grafting. Periosteal grafting is considered to be potentially valuable as a boneless bone grafting technique.

Animals↗

PubMed1996

Electrical stimulation at traditional acupuncture sites in periphery produces brain opioid-receptor-mediated antinociception in rats.

Previous studies in rats measuring latency to tail flick with radiant heat have shown that the antinociceptive effect induced by electrical stimulation of different frequencies at traditional acupuncture sites is mediated via different opioid receptors in the spinal cord. The present study was designed to observe (1) whether electrical stimulation at such sites could produce antinociceptive effects in the cold water tail-flick (CWT) test; (2) whether the antinociceptive effects could be blocked by s.c. injection of the opioid receptor antagonist naloxone and (3) whether i.c.v. injection of selective antagonists for mu (cyclic D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, CTAP), delta (naltrindole) or kappa (nor-binaltorphimine) opioid receptors would block the antinociceptive effect produced by electrical stimulation. Sprague-Dawley rats were stimulated at frequencies of 2, 30 or 100 Hz with acupuncture needles inserted into acupoints Zusanli and Sanyinjiao in the hind leg for 30 min. Antinociception was assayed in the CWT. The results showed that (1) a significant, frequency-related increase in threshold in the CWT was observed in all electrical stimulation groups as compared with the placebo group and the antinociceptive effect lasted about 30 min poststimulation; (2) naloxone (s.c.) antagonized the antinociceptive effect induced by 2 Hz, 30 Hz or 100 Hz electrical stimulation and (3) either CTAP or naltrindole (i.c.v.) almost completely blocked the antinociceptive effect induced by 2 Hz or 30 Hz electrical stimulation, but was less effective in blocking antinociception induced by 100 Hz electrical stimulation; nor-binaltorphimine (i.c.v.) greatly reduced antinociception induced by 30 Hz or 100 Hz electrical stimulation, but not by 2 Hz electrical stimulation. These results indicate that the antinociception induced by 2 Hz electrical stimulation is mediated by both mu and delta opioid receptors; the antinociception induced by 100 Hz electrical stimulation is mediated primarily by the kappa receptor; and the antinociception induced by 30 Hz electrical stimulation is mediated by all three opioid receptor types. Thus, the antinociceptive effect induced by peripheral electrical stimulation, as measured by the CWT, involves opioid receptors in the rat brain.

Acupuncture Therapy↗