High Electrical Stimulation Research Articles

Alternating Electric Fields Modify the Function of Human Osteoblasts Growing on and in the Surroundings of Titanium Electrodes.

Endogenous electric fields created in bone tissue as a response to mechanical loading are known to influence the activity and differentiation of bone and precursor cells. Thus, electrical stimulation offers an adjunct therapy option for the promotion of bone regeneration. Understanding the influence of electric fields on bone cell function and the identification of suitable electrical stimulation parameters are crucial for the clinical success of stimulation therapy. Therefore, we investigated the impact of alternating electric fields on human osteoblasts that were seeded on titanium electrodes, which delivered the electrical stimulation. Moreover, osteoblasts were seeded on collagen-coated coverslips near the electrodes, representing the bone stock surrounding the implant. Next, 0.2 V, 1.4 V, or 2.8 V were applied to the in vitro system with 20 Hz frequency. After one, three, and seven days, the osteoblast morphology and expression of osteogenic genes were analysed. The actin organisation, as well as the proliferation, were not affected by the electrical stimulation. Changes in the gene expression and protein accumulation after electrical stimulation were voltage-dependent. After three days, the osteogenic gene expression and alkaline phosphatase activity were up to 2.35-fold higher following the electrical stimulation with 0.2 V and 1.4 V on electrodes and coverslips compared to controls. Furthermore, collagen type I mRNA, as well as the amount of the C-terminal propeptide of collagen type I were increased after the stimulation with 0.2 V and 1.4 V, while the higher electrical stimulation with 2.8 V led to decreased levels, especially on the electrodes.

Noradrenaline-Induced Restoration of Acidosis-Inhibited Neurogenic Vasoreactivity at Using Different Electrical Stimulation Frequencies

Experiments using segments of the tail artery from young rats addressed the effects of noradrenaline on the neurogenic vasoconstrictor reactions of these segments evoked by stimulation with an electric field of frequencies 3, 5, 10, and 40 Hz in controls and after decreasing the solution pH from 7.4 to 6.6. Acidosis produced significant decreases in this reaction at all electrical stimulation frequencies. Noradrenaline restored neurogenic vasoconstriction after it had decreased spontaneously or after the significantly greater drop induced by acidosis. On the background of acidosis, the potentiating action of noradrenaline on neurogenic vasoconstriction was more significant than at normal pH and was more apparent at higher electrical stimulation frequencies and noradrenaline concentrations. This may be of value for redistributing blood flow to vitally important areas during muscle work, which is accompanied by acidosis, increased spike frequencies in sympathetic nerves, and increases in noradrenaline concentrations.

Hearing Loss After Activation of Hearing Preservation Cochlear Implants Might Be Related to Afferent Cochlear Innervation Injury.

Characterize hearing loss (HL) after hearing preservation cochlear implantation and determine the association between high charge electrical stimulation (ES) and late loss of acoustic hearing. A retrospective cohort analysis of all hearing preservation implantees at our center (n = 42) assayed HL as a function of maximum charge. We analyzed serial audiometry from 85 patients enrolled in the multicenter Hybrid S8 trial to detail the hearing loss greater than 1 month after implantation. Cochleotypic explant cultures were used to assess susceptibility to high levels of ES. Early HL after implantation tends to be mild and averages 12.2 dB. After activation of the Hybrid S8 device, 17 (20%) of 85 patients experienced acceleration of HL. Compared with the majority of patients who did not lose significant hearing after activation, these patients experienced more severe HL at 1 year. Five patients implanted at our center experienced acceleration of HL after high charge exposure. In patients implanted at our center, high charge was associated with late HL (Pearson 0.366, p = 0.016). In rat cochleotypic explants, high voltage ES damaged afferent nerve fibers, reflected by blebbing and a 50% reduction in the number of fibers innervating the organ of Corti. In contrast, hair cells displayed only minor differences in cell number and morphology. Based on clinical and in vitro data, we theorize that the combination of acoustic amplification and ES in the setting of intact hair cells and neural architecture may contribute, in part, to cochlear toxicity, perhaps by damaging the afferent innervation.

Electrical Stimulation Reduces Apoptotic Signaling in SGNs

Objective: To establish the intracellular consequences of electrical stimulation (ES) to spiral ganglion neurons (SGNs) after deafferentation. SGNs die as a result of loss of hair cells, their sole afferent input. Some histologic animal studies of chronic ES after deafening show that ES alone may improve SGN survival. Here we use a rat model to determine the effect of both low and high pulse rate ES on activation of the pro-apoptotic transcription factor Jun in deafferented SGNs in vivo. Methods: A single electrode was implanted through the round window of kanamycin-deafened rats at either postnatal day 32 (P32) or P60 for 4 hours of ES (monopolar, biphasic pulses, amplitude twice eABR threshold) at either 100 or 5000 Hz. Jun phosphorylation, a proapoptotic signaling event known to occur in apoptotic SGNs after deafening, was assayed by immunofluorescence to quantitatively assess the effect of ES on proapoptotic signaling. Results: Jun phosphorylation was reliably suppressed by 100 Hz ES in deafened cochleae of P32 rats ( P = .045) but this effect was less robust when 5000 Hz ES was used. This effect was most significant in the cochlear turn just apical to the stimulating electrode and was not significant in P60 rats. Conclusion: Suppression of phospho-Jun occurs in deafferented SGNs after only 4 hours of ES, consistent with the hypothesis that ES provides trophic support to SGNs after deafferentation. Stimulation frequency may be consequential: 100 Hz ES was significantly more effective than 5000 Hz ES in suppressing phospho-Jun.

Modality specific alterations of esophageal sensitivity caused by longstanding diabetes mellitus

Abstract Background Abnormal visceral sensory function has been demonstrated in patients with diabetes mellitus and diabetic autonomic neuropathy seems to be involved in the development and progression of gastrointestinal tract dysfunction. The possibility of multimodal (e.g. mechanical, electrical, thermal and chemical) stimulation in, e.g. the esophagus has developed visceral pain research. The major advantage is involvement of distinctive receptors, various sensory nerves and different pain pathways mimicking clinical pain that favours investigation of central pain mechanisms involved in allodynia and hyperalgesia. Hence the rationale of the presents study was to explore the nervous system by assessment of esophageal sensitivity to multimodal stimulations. Methods Throughout an euglycemic clamp, 31 healthy volunteers (age 44.3 ± 10.6 (mean ± SD) years; 11men) and 31 patients (age 46.3 ± 11.7 years; 10 men) with insulin dependent diabetes mellitus (duration 31.3 ± 13.1 years) were included in the study. By use of a multimodal oesophageal probe, sensitivity to heat, mechanical distension and electrical stimulation was assessed in the lower oesophagus. Results For heat stimulation patients had increased sensitivity in the sensory range with shorter stimulus duration until pain tolerance threshold (122 ± 3.8 sec vs. 136 ± 3.7 sec; p = 0.006) and larger area under the temperature curve (2380 ± 1847 vs. 1409 ± 1450; p = 0.03). There were no differences between groups for mechanical stimulation (maximum pressure (39 ± 57mmHg vs. 24 ± 48mmHg; p = 0.3; maximum volume 59 ± 21ml vs. 62 ± 25 ml; p = 0.56). As an overall finding, patients tolerated higher electrical stimulation intensities (p = 0.02), dominated by discrimination in the sensory range: At sensory detection threshold (VAS1) 21.1 ± 12.4 mA vs. 16.3 ± 5.5 mA (p = 0.03); at moderate sensation (VAS3) 27.5 ± 13.3 mA vs. 21.5 ± 5.0 mA (p = 0.03) however at pain detection threshold (VAS5) 31.6 ± 13.1mA vs. 28.8 ± 5.2 mA; the trend was insignificant (p = 0.3). Conclusion Patients with insulin dependent diabetes mellitus had modality-specific alterations of esophageal sensitivity. Heat stimulation activates selectively mucosal receptors whereas on the contrary electrical stimulation depolarizes the free nerve endings non-selectively. Hence, due to the different sensitivity profile, the esophageal neuropathy is most likely a result of both peripheral and central neuropathy caused by longstanding diabetic neuronal damage.

Effect of repetitive transcranial magnetic stimulation on rectal function and emotion in humans

A previous brain imaging study demonstrated activation of the right dorsolateral prefrontal cortex (DLPFC) during visceral nociception, and this activation was associated with anxiety. We hypothesized that functional modulation of the right DLPFC by repetitive transcranial magnetic stimulation (rTMS) can reveal the actual role of right DLPFC in brain-gut interactions in humans. Subjects were 11 healthy males aged 23.5±1.4 (mean±SE) years. Viscerosensory evoked potential (VEP) with sham (0mA) or actual (30mA) electrical stimulation (ES) of the rectum was taken after sham, low frequency rTMS at 0.1Hz, and high frequency rTMS at 10Hz to the right DLPFC. Rectal tone was measured with a rectal barostat. Visceral perception and emotion were analyzed using an ordinate scale, rectal barostat, and VEP. Low frequency rTMS significantly reduced anxiety evoked by ES at 30mA (p<0.05). High frequency rTMS-30mA ES significantly produced more phasic volume events than sham rTMS-30mA ES (p<0.05). We successfully modulated the gastrointestinal function of healthy individuals through rTMS to the right DLPFC. Thus, rTMS to the DLPFC appears to modulate the affective, but not direct, component of visceral perception and motility of the rectum.

Effects of postmortem carcass electrical stimulation on goat meat quality characteristics

Electrical stimulation (ES) has been reported to improve meat quality, but the effects of postmortem ES have not been fully characterized in goats. This experiment was conducted to determine the effects of postmortem ES on meat quality in two breeds of goats. Uncastrated Spanish and crossbreds (Boer × Spanish females × Kiko male) yearlings ( n = 10/breed, body weight 31.2 ± 2.43 kg) were transported to the slaughter facility, held overnight in pens without feed, and slaughtered on two different days. Immediately after slaughter each carcass was split into two halves along the vertebral column. The left half was subjected to a high voltage ES (580 V) at 5 s intervals during 120 s (treatment) and the right half was kept as a non-stimulated control. After 24 h of cooler storage (2 °C), the carcasses were fabricated into 2.5 cm-thick loin/rib chops. Longissimus dorsi (LD) muscle pH and temperatures were recorded at 0, 1, 2, 3, 4, 5, 6, 9, 12, 15, 18, and 24 h postmortem. The pH values of LD muscle were lower in stimulated sides than control sides ( P < 0.01), and pH decreased quadratically ( P < 0.01) with advancing time during the 24 h postmortem period. Treatment had no significant effect on the LD muscle temperature, and the temperature decline followed a cubic pattern ( P < 0.01) during the 24 h postmortem period. Muscle glycogen concentrations immediately after electrical stimulation (0 h) were lower ( P < 0.05) in the stimulated sides compared to control sides. Warner-Bratzler shear force (WBSF) values of loin chops were lower ( P < 0.01) in stimulated sides (3.0 kg) compared to control sides (4.2 kg), and the chops from Spanish goats (3.9 kg) had higher ( P < 0.05) WBSF values compared with crossbreds (3.3 kg). Color values ( L*, a*, b*, chroma, and hue angle) and sarcomere length were not affected by ES or breed. Heated calpastatin activities were not influenced by ES, but the activities were lower at day 4 compared with day 1 of aging ( P < 0.05). There were no significant effects ( P > 0.05) of ES or aging time on selected myofibrillar protein concentrations (myosin heavy chain, myomesin, desmin, actin, troponin-T, and myosin light chain, P > 0.05). However, desmin concentration tended to decrease at day 4 of aging ( P = 0.08). The results indicate that ES significantly accelerated postmortem glycolysis and improved tenderness of loin chops, as indicated by WBSF values.

Neuromuscular fatigue and recovery dynamics following prolonged continuous run at anaerobic threshold

Objective: The aim of this study was to determine the influence of intensive aerobic running on some muscle contractile characteristics and the dynamics of their recovery during a 2 hour...

Functionality of electrically stimulated broiler breast meat1

Postmortem electrical stimulation (ES) tenderizes meat by acceleration of adenosine triphosphate (ATP) depletion, pH decline, and physical disruption of muscle fibers. It has been demonstrated that rigor development at elevated temperatures, as with slow chilling, can cause meat to develop pale color and poor water-holding capacity. The objective of this study was to compare the functionality of broiler breast meat from control and electrically stimulated carcasses with and without normal rapid chilling. Broilers were either electrically stimulated (450 mA, 450 V, 2 s on, 2 s off for 7 pulses) immediately after bleeding or used as nonstimulated controls. The ES birds were either chilled immediately (ES2) or had chilling delayed for 2 h at room temperature (ESD2). All ES breast fillets were harvested at 2 h postmortem. The control carcasses were chilled immediately and had fillets harvested at 2 h postmortem (C2) or at 8 h postmortem (C8). Electrical stimulation accelerated pH decline and prevented toughening when breast meat was deboned at 2 h postmortem, regardless of chilling rate. The water released from the gels during cooking was higher for the ESD2 than the ES2 group, which was not different from the C2 group, suggesting that ES followed by slow chilling reduced water-holding capacity compared with the ES2 and C2 groups. There were no differences in expressible moisture, gel strength, or lightness among the ES2, ESD2, and C2 treatments. These results indicated that high voltage ES followed by normal chilling did not impair protein functionality or cause pale, soft, exudative meat. However, there was some evidence that slow chilling after ES may negatively affect some water-holding properties of the meat.

Age-related changes in sympathetic modulation of sensory nerve activity in rat skin.

Sensory nerves play an important role in mediating neurogenic inflammation and subsequent tissue healing. A decrease in sensory nerve function with increasing age has been reported to correlate with poor tissue healing. Sympathetic nerves are known to modulate sensory nerve function, and changes in this modulation could also have important implications with ageing. The aims of this study were to examine the effect of different frequency electrical stimulation (ES) on the microvascular responses obtained to sensory nerve activation in young, aged and capsaicin-pretreated rats and modulation of these responses by sympathetic efferents. Using laser Doppler flowmetry, vascular responses to antidromic ES of the sciatic nerve were monitored in the base of vacuum-induced blisters in the hind footpad. The non-selective alpha-adrenoceptor antagonist phentolamine (3 mg/kg, i.v.) was administered 20 min prior to ES. At high frequency ES (20V, 2ms, 15Hz for 1 min), the vascular response in old rats was significantly reduced (46 percent decrease, p < 0.05) compared to young control. At low frequency ES (20 V, 2 ms, 5 Hz for 1 min) however, older rats produced similar vascular responses to the young. Capsaicin-pretreated rats showed significantly reduced vascular responses to both high and low frequency ES, regardless of age. Pretreatment with phentolamine significantly increased the microvascular response in young rats at high (87 percent) and low (36 percent) frequency ES. In contrast, phentolamine significantly increased the ES-induced response in old rats at high frequency only (147 percent increase). The results suggest that the aged sensory nerve responds preferentially to low frequency ES and that sympathetic efferents exert an inhibitory modulatory effect on the vascular response evoked by sensory nerve stimulation. There are age-related changes in sympathetic modulation of sensory nerve-mediated responses which is dependent on stimulation frequency.

Improving pork quality by electricalstimulation or pelvic suspension ofcarcasses

This investigation compared the separate and combined effects on meat quality of electrical stimulation (ES) and pelvic suspension of pig carcasses chilled rapidly or conventionally. Sides from 80 pigs, 80–90 kg live weight, were allocated to one of four treatments followed by either conventional chilling (1°C for 24 h) or rapid chilling (-20°C for 2–3 h, before 1°C until 24 h post-slaughter). The four treatments were: Achilles suspended, with and without high voltage ES, and pelvic suspended, with and without ES. The quality attributes: pH, colour and opacity, drip loss, instrumental and sensory texture were measured in M. longissimus thoracis et lumborum, at 10 days post-slaughter. Rapid chilling reduced the evaporative weight loss by 0·5% There were no significant effects of treatment on colour or opacity, although ES samples were slightly paler. Drip loss was also slightly greater with ES, particularly when combined with pelvic suspension, but in no case was the meat classified as PSE. Instrumental measurements of 'texture showed improved tenderness from both ES and pelvic suspension, even after 10 days ageing. The improvement was less pronounced when ES and pelvic suspension were combined Taste panelling confirmed that samples treated by ES or pelvic suspension, separately or combined, were significantly more tender than samples from non-ES, Achilles hung sides. ES and pelvic suspension were equally effective in improving the tenderness of pork loin. Pelvic suspension did not suffer the disadvantage of increased drip loss that occurred with ES in this study.

Influence of production and postmortem technologies on composition and palatability of USDA Select grade beef

Improvement of USDA Select grade beef is essential for consumer acceptance of leaner beef. Seventy-two large- and medium-framed steer calves of mixed breeding were used in two experiments to evaluate feedlot performance, carcass composition, and beef palatability. Interactions of dietary energy level (corn concentrate or corn silage), breed type (Angus or Simmental), carcass electrical stimulation (ES) voltage (low or high), and chilling rate (normal or delayed) were determined. Grain-fed cattle had similar initial and slaughter weights, heavier carcasses, more marbling, higher quality grades, and higher dressing percentages (Exp. 2) compared with silage-fed cattle, even though all cattle were visually selected for a constant grade end point. Simmental cattle had heavier initial slaughter and warm carcass weights, larger loin eye area, less fat depth, and lower yield grade than Angus cattle. Percentage of lean in the 9-10-11th rib was lower and percentage of fat was higher for grain-fed and Angus steers than for silage-fed and Simmental steers, respectively. Neither diet nor breed influenced chemical composition of the edible portion, except that separable lean in Angus steers was higher in ether extract. No differences in palatability existed between Angus and Simmental steaks. High ES voltage compared with low voltage improved some tenderness characteristics and reduced some juiciness scores. The USDA Select grade beef of accepted palatability can be produced on either corn-grain or corn-silage diets, and only minor differences in beef palatability in such cattle are caused by ES voltage.

Cutaneous versus Muscular Perception of Electrically Evoked Tetanic Pain

This work was supported in part by Laval University (sabbatical leave of Dr. A.Y. Bélanger), the School of Kinesiology at Simon Fraser University, and Medtronic of Canada Inc. There is much speculation in athletic, physical therapy, and sports medicine circles about the relative cutaneous (superficial) vs. muscular (deep) perception of pain felt during maximum electrically evoked tetanic muscle contraction. To date, very few studies have addressed the basic question of whether pain perception during electrical stimulation is more superficial (cutaneous) or deep in muscular tissue. The purpose of this study was to determine, in a group of 10 healthy male subjects, the effect of a complete sensory nerve block at the thigh on the qualities (intensity, sensory, affective) of pain (elicited by electrically induced tetanic muscle contraction) as measured by the Short-Form McGill Pain Questionnaire felt during high amplitude, 50-Hz electrical stimulation (ES) of the vastus lateralis muscle. The findings from this study provide clear evidence that a healthy individual's tolerance level to pain induced during electrically evoked maximum tetanic muscle contraction depends as much on deep muscle stimulation as it does on cutaneous or superficial stimulation. Indeed, the results show a statistically significant decrease of approximately 50% in all three qualities of pain (intensity, sensory, and affective) following the elimination of cutaneous pain pathways via the nerve blocking procedure (p < 0.05). Until it is demonstrated that the same results hold for patients who often experience pain prior to ES treatments, any clinical implications would seem to be premature. For now, clinicians must be aware that muscle, as much as skin, may limit one's ability to tolerate high amplitude ES treatments. Further research is needed on the cutaneous vs. muscular perception of electrically evoked pain in healthy and diseased populations as well as on the issue of subject and patient experience vs. nonexperience with ES. J Orthop Sports Phys Ther 1992;16(4):162-168.

Spreading depression produced in the thalamus, hippocampus, and caudate nucleus by electrical stimulation of the parietal cortex in rats

The parameters of cortical electrical stimulation (ES) producing synaptically-operated spreading depression (SD) were determined in rats. Waves of SD were regularly triggered in the thalamus by brief, high frequency ES (0.02–0.05 sec; 200–500 Hz) of the parietal cortex. Monitoring by EEG confirmed the lack of accompanying convulsive activity in the cortex and the subcortical structures investigated. Use of Nembutal-induced anesthesia led to a higher minimum threshold for onset of SD, without preventing short-latency thalamid SD. Stimulating the parietal cortex was less effective for synaptic excitation of hippocampal and caudate SD. Hippocampal, unlike thalamic SD, was accompanied by spells of epileptiform activity, most pronounced at certain points in the onset and decline of the SD wave. These brief convulsive episodes were not the cause but the result of SD to a large extent. The low, subconvulsive threshold of synaptically triggered subcortical as well as cortical structures should therefore be taken into account when considering the functional significance of the SD reaction.