High-voltage Stimulation Research Articles

Biochemical and Structural Effects of Rigor Mortis-Accelerating Treatments in Broiler Pectoralis

This study was conducted to elucidate the mechanism of action of two selected rigor mortis-accelerating treatment systems employed in the prevention of the toughness associated with early-harvested (1 h post-mortem) broiler Pectoralis muscle. The treatments included 14 min of low voltage electrical stimulation (110 V, 1 A, pulsing 1 s on and 1 s off) combined with high temperature conditioning (39 C) and muscle tensioning (LV + HTC + MT); a 15-s high voltage stimulation (440 V, 1 A pulsing 2 s on and 1 s off) combined with muscle tensioning (HV + MT); and a control simulating commercial broiler processing practices. The rigor-accelerating treatments reduced pH and increased R-value (inosine:adenosine ratio) at 1 h post-mortem, but only the LV + HTC + MT treatment reduced sarcomere shortening. Both rigor treatments reduced the amount of measurable myofibrillar fragmentation. Cathepsin B and B + L activities were not affected by the rigor treatments. Calpain I activity was not detectable in any 24-h post-mortem sample. Calpain II activity at 24 h post-mortem was greater in muscles receiving HV + MT than from the LV + HTC + MT or control carcasses, but was reduced in all muscles by 24 h postmortem. An SDS-PAGE indicated a 30-kDa polypeptide that was absent at death and appeared in control and LV + HTC + MT muscles but to a lesser extent in HV + MT muscles. These results suggested that the LV + HTC + MT treatment has a greater tenderizing effect than the HV + MT treatment because the former achieves a better balance between reduced sarcomere shortening and myofibrillar fragmentation.

Effects of electrical stimulation on lymphatic flow and limb volume in the rat.

The mechanism by which electrical stimulation affects edema has not been elucidated. The purpose of this study was to determine whether subcontraction high-voltage stimulation (SC-HVS) (ie, electrical stimulation that did not elicit a visible contraction) applied to the right hind limbs of rats would (1) alter the rate of lymphatic uptake of injected albumin labeled with Evans blue dye (AL-EBD) and (2) affect experimentally induced edema. The paws of 28 anesthetized Sprague-Dawley rats (mean weight = 263 g, SD = 48 g) were injected with AL-EBD. The experimental group (n = 13) received 1 hour of SC-HVS, and the control group (n = 15) received sham treatment consisting of the same treatment administered to the experimental group but without the SC-HVS. Blood samples and volume measurements were obtained at intervals over a 7-hour period. Analysis of variance and post hoc testing indicated that higher amounts of AL-EBD were taken up by the lymph of the experimental group animals as compared with the control group animals at each time period following the treatment. The experimental group's AL-EBD reached significance immediately after treatment, whereas the control group required an additional 4 hours. There was no significant reduction in limb volume in either group. The SC-HVS significantly increased the uptake of AL-EBD by lymphatic vessels, but it did not cause a significant decrease in the induced edema. The results of this study indicate that SC-HVS has the potential to reduce edema by increasing lymphatic uptake of proteins.

The efficacy of high and low voltage electrical stimulation under different chilling regimes

Two experiments were conducted to determine the efficacy, in terms of beef quality, of low voltage (LV), high voltage (HV) and combined low and high voltage (LH) electrical stimulation under two chilling regimes (blast chilling, BC; conventional chilling, CC).In both experiments, regardless of the type of electrical stimulation, shear values were significantly lower (P < 0.01) in stimulated carcasses compared with non-stimulated control carcasses (CON). Despite the results of the objective measures of shear, taste panel data from exp. 1 indicated a preference for steaks from treatments subjected to high voltage stimulation (HV and LH; P < 0.01). Colour of the musculature in electrically stimulated carcasses was significantly lighter and brighter than CON carcasses in both experiments. However, in exp. 2, where LV was applied for 40 s, a small proportion (~ 10%) of the carcass sides exhibited a pale, soft, exudative condition. This was reflected in the significantly higher drip losses in the LH and LV treatments in exp. 2. Overall, these results indicate an advantage of HV over LV stimulation. Since high voltage stimulation resulted in improved objective measures of meat quality and improved palatability, its use can be recommended to Canadian packers.Under the blast chilling conditions employed in the present studies there were no significant interactive effects with electrical stimulation. Blast chilling resulted in a significant reduction in cooler shrink (P < 0.01), a darker meat colour (P < 0.01) and slightly higher shear force values. The small magnitude of the increase in shear force (approximately 0.3 kg) was not identified by the taste panel and is unlikely to be detected by consumers. Key words: Beef quality, high voltage, low voltage, electrical stimulation

Neutron Burst from a High-Voltage Discharge between Palladium Electrodes in D2Gas

In this paper a recent experimental observation of a neutron flux burst at a rate of 2 {times} 10{sup 4} times the background rate during a high ac voltage stimulation between two deuterated palladium electrodes in D{sub 2} gas is explained in terms of the experimentally measured deuterium-deuterium (D-D) fusion cross sections. Theoretical criteria and experimental conditions for improving D-D fusion rates with the use of pulsed high-dc voltages are described.

Autonomic nervous control of nasal vasculature and airflow resistance in the anaesthetized dog.

1. In pentobarbitone-anaesthetized dogs with constant-flow vascular perfusion of nasal mucosa on both sides, nasal airway resistance, vascular resistance, vascular capacitance (via changes in total venous outflow) and blood flow in the anterior and posterior venous systems were measured. 2. Electrical stimulation of the cut peripheral ends of the cervical sympathetic trunk, caudal nasal nerve, or major palatine nerve increased vascular resistance and decreased vascular capacitance and airway resistance. Propranolol and atropine had no effect on the responses while bretylium completely abolished them; phentolamine greatly lessened the vascular resistance response and partially decreased the vascular capacitance and airway responses. Hence, sympathetic stimulation causes constriction of the resistance vessels via alpha-adrenergic mechanism and constriction of capacitance vessels via alpha-adrenergic as well as some non-adrenergic and non-cholinergic mechanisms. 3. Denervation of the cervical sympathetic trunk, caudal nasal nerve and major palatine nerve decreased nasal vascular resistance and increased vascular capacitance and airway resistance, suggesting tonic sympathetic discharge to nasal mucosa via caudal nasal and major palatine nerves. 4. Electrical stimulation of the nerve of pterygoid canal decreased vascular resistance but increased vascular capacitance (in the posterior venous system) and airway resistance to low-voltage stimulation (below 10 V), and decreased vascular capacitance (in the anterior venous system) and airway resistance to high-voltage stimulation (above 10 V). Hexamethonium reversed the vascular resistance response as well as vascular capacitance and airway responses to high-voltage stimulation. Bretylium and phentolamine enhanced the vascular resistance response and reversed vascular capacitance and airway resistance responses to high-voltage stimulation. Hence, low-voltage stimulation results in parasympathetic dilatation of resistance and capacitance vessels whereas high-voltage stimulation results in parasympathetic dilatation of resistance vessels and sympathetic constriction of capacitance vessels. The parasympathetic vasodilatation was atropine resistance and the sympathetic vasoconstriction was partially via alpha-adrenergic mechanisms. 5. Denervation of the nerve of pterygoid canal did not affect vascular resistance, vascular capacitance or airway resistance suggesting negligible tonic parasympathetic and sympathetic discharges to nasal blood vessels via the nerve. 6. Simultaneous optimal stimulation of sympathetic and parasympathetic nerves resulted in vasoconstriction, especially in capacitance vessels, suggesting sympathetic predominance over parasympathetic control.

Polarity effects on wound healing using electric stimulation in rabbits.

The aims of this study were to examine effects of high-voltage stimulation (HVS) on wound closure, tensile properties, and mitotic activity. Thirty-six rabbits were assigned to experimental (n = 18) or control groups. Each animal was anesthetized and a full-thickness incision, 3.5 cm long, was made on its back. After 24 hours, experimental rabbits received HVS for two hours, twice daily, for seven days. Polarity was negative the first three days and positive thereafter. Wound closure for HVS treated rabbits was 100%, which was significantly better than that of control rabbits (87%). Tensile strength values and mitotic activity for experimental and control rabbits were comparable. Histologic examination of the wounds suggested a more rapid rate of epithelialization in treated rabbits. Results suggest that electric stimulation, as given, augments wound closure.

High-voltage stimulation over the human spinal cord: sources of latency variation.

Percutaneous electrical stimuli (up to 600 V) were applied over the cervical spinal cord to evoke responses in the biceps brachii and thenar muscles. Cathodal stimulation over the C7 spinous process was more effective than anodal stimulation or stimulation over the C5 or C3 spinous process. As the stimulus intensity was increased, the response amplitude increased and the latency decreased. When progressively higher levels of supramaximal stimuli were delivered the latency often decreased further. The shortest latencies evoked by stimulation over the C7 spinous process were close to the latencies of the responses evoked by supramaximal stimulation near Erb's point. Thus, with this type of stimulation, the site of nerve activation changes with different stimulus intensities. The variability in latency introduced by distal spread of the site of activation will affect measurements of central motor conduction time and should be considered in the diagnostic use of this technique.

Effect of nifedipine on the contractile function of the rat diaphragm in vitro

The isometric contractile response of the directly- stimulated rat diaphragm was studied before and following addition of the calcium channel blocker, nifedipine. Nifedipine (10 ug/ml and 30 ug/ml bath concentrations) significantly increased isometric force output during twitch and unfused tetanic stimulation. Force potentiation during unfused tetanic stimulation was equivalent during either high or low voltage stimulation. Nifedepine had no effect on the time to peak force, half relaxation time, or relaxation time during twitch stimulation; thus, both activation and relaxation rates were increased. The force potentiating actions of nifedipine persisted in a calcium-free bathing solution and were enhanced by d-tubocurarine. In contrast to the force enhancing effects found with twitch and unfused tetanic stimulation, nifedipine caused a small but significant reduction in isometric force during maximal fused tetanic stimulation. It is concluded that the force potentiating effects of nifedipine on rat diaphragm are not due to fiber recruitment, enhancement of neuromuscular excitation, or altered inward trans-sarcolemmal calcium flux, but may result from a direct effect of the drug on the rate of activation of the contractile apparatus.

Effect of High Voltage Pulsed Electrical Stimulation on Microvascular Permeability to Plasma Proteins

The purpose of this study was to determine whether high voltage pulsed electrical stimulation reduces microvascular permeability to plasma proteins in a simulation of acute edema. Fourteen male golden hamsters were anesthetized and prepared for fluorescence microscopy of the cheek pouch. Intravenous fluorescein-labeled dextran (MW 150,000) served as a tracer of plasma proteins. Protein leaks from the microvessels were quantified every 5 minutes for a 25-minute baseline period and again after a 5-minute superfusion with 10(-5)-M histamine. High voltage stimulation (HVS) was applied simultaneously with the histamine to the vascular bed of the treatment animals in a dosage of 10, 30, or 50 V; the control animals received no electrical stimulation. Histamine increased microvessel leakiness in all groups, but the number of posthistamine microvessel leaks was significantly less in animals that received a 30- or 50-V dose of HVS than in the control animals or those that received a 10-V dose. The study results suggest that at intensities greater than a threshold dose, HVS reduces microvessel leakiness. Reduced microvessel leakiness may be one mechanism by which HVS retards edema formation.

High Voltage Stimulation: An Integrated Approach to Clinical Electrotherapy

High Voltage Stimulation: An Integrated Approach to Clinical Electrotherapy

Effects of high voltage pulsed electrical stimulation on blood flow.

The purpose of this study was to determine whether high voltage electrical stimulation would increase blood flow to skeletal muscle in healthy subjects. Subjects were assigned to one of three groups: 1) an Electrical Stimulation (ES) Group (n = 16), 2) an Exercise (EX) Group (n = 14), or 3) a Control Group (n = 8). Isometric contractions were induced electrically at 30 Hz in the ES Group and performed volitionally in the EX Group for five minutes at intensities of 10% and 30% of predetermined maximal voluntary isometric contraction (MVC) efforts. Blood flow, heart rate, and blood pressure were unaffected in the ES Group, but blood flow and systolic blood pressure increased and decreased, respectively, for the EX Group at 30% of MVC. High voltage stimulation at a pulse rate of 30 Hz and at intensities needed to evoke contractions at 10% and 30% of MVC for plantar flexion did not increase blood flow at the popliteal artery.

Effect of high voltage stimulation on edema reduction in the rat hind limb.

The purpose of this study was to test the effect of high voltage stimulation (HVS) on edema reduction in the rat hindpaw. The animals were divided into a control group (n = 20) and a treated group (n = 20). The right hindpaw volume was measured, and then the animal's paw was traumatized. The animals in the treated group were treated with HVS at 24, 48, and 72 hours posttrauma. Paw volume measurements were made on all animals at 0, 24, 48, 72, and 96 hours posttrauma. In addition, the paw volume was measured in the treated group both before and after HVS. The results showed that animals in both groups had a significant decrease in paw volume over the experimental period, but no significant difference was found between the two groups in the amount of edema reduction. The HVS treatment did not produce a significant change in paw volume immediately after treatment.

Tenderness and Physical Characteristics of Broiler Breast Fillets Harvested at Various Times from Post-Mortem Electrically Stimulated Carcasses

In three experiments, tenderness and various physical characteristics were determined for broiler breast fillets harvested after picking (hot boning), after chilling (chill boning), or after a 48-h aging period (aged boning) from high (240, 530, 820 V) or low (45 V) voltage electrically stimulated carcasses. Electrical stimulation was applied within 2 to 3 min post-mortem.Low voltage post-mortem electrical stimulation, regardless of tested duration, significantly decreased toughness of hot-boned breast meat. High voltage electrical stimulation, regardless of voltage or duration, had no significant effect on the tenderness or moisture content of hot-boned or aged-boned fillets. Stimulation significantly increased absorbance values and decreased pH at time of hot boning and chill boning but had no effect on these characteristics in aged-boned fillets. High voltage stimulation (820 V) significantly decreased shear values and increased sarcomere lengths of chill-boned breast fillets producing an acceptable level of tenderness. The data from the three experiments indicated that low voltage (45 V) electrical stimulation improved tenderness of hot-boned fillets; however, high voltage electrical stimulation (820 V) was required to produce a tenderizing response in chill-boned fillets. Tenderness response was more highly related to myofibrillar disruption and increased sarcomere length than to pH or ATP disappearance (absorbance ratio) and was of sufficient magnitude to alleviate toughness associated with chill-bone fillet products.

Evidence for inhibition by ICS 205-930 and stimulation by BRL 34915 of K+ conductance in cardiac muscle

Electrophysiological effects of the 5-HT3 receptor antagonist ICS 205-930 [(3 alpha-tropanyl)-1H-indole-3-carboxylic acid ester] were investigated in guinea pig isolated heart preparations. ICS 205-930 prolonged the functional refractory period and decreased the force of contraction in left driven atria. It decreased spontaneous beating rate in right atria. These effects were concentration dependent between 3 X 10(-6) and 10(-4) mol/l of ICS 205-930. In fast action potentials of papillary muscles ICS 205-930 concentration-dependently depressed Vmax and prolonged the action potential duration (APD) between 10(-6) and 10(-5) mol/l. The action potential amplitude (APA) and the resting membrane potential (RMP) remained unchanged. In papillary muscles partially depolarized by high K+ (22 mmol/l) and reactivated by high voltage stimulation, slow response APs were prolonged by ICS 205-930 10(-6) to 3 X 10(-5) mol. Vmax, APA and RMP were not affected. Similar effects on APD were obtained with sotalol (3 X 10(-5) mol/l), an inhibitor of outward K+ current. The slow-APD prolongation induced by ICS 205-930 as well as by sotalol was reversed by BRL 34915 (6-cyano-3,4-dihydro-2,2-dimethyltrans-4-(2-oxo-1-pyrrolidyl )-2H-benzo[b]pyran-3-ol), known to open K+ channels. BRL 34915 alone reduced slow-APD stereoselectively. The results suggest that ICS 205-930 may inhibit and BRL 34915 may stimulate the K+ conductance of guinea pig myocardial cell membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of high voltage stimulation on cutaneous wound healing in rabbits.

The primary purpose of this study was to determine whether high voltage stimulation (HVS) enhances wound healing. Forty female rabbits were assigned to experimental or control groups and followed for four or seven days. We classified the groups as Exp4, Con4, Exp7, and Con7, respectively. Each animal was anesthetized, and a full-thickness incision, 3.5-cm long, was made on its back. After 24 hours, Exp4 and Exp7 rabbits received HVS with a negative polarity for two hours twice daily. Although tensile-strength values were 36% higher for Exp4 rabbits than for Con4 rabbits, no significant differences in tensile strength or percentage of wound closure existed between the two groups. After seven days, Con7 rabbits had a higher percentage of wound closure and significantly greater tensile-strength measures than Exp7 rabbits. Histologic examination of the wounds did not provide clear-cut evidence of differences between the experimental and control groups. Results suggest that 1) HVS did not significantly improve wound healing for Exp4 rabbits and 2) HVS as given, may have hampered the healing process for Exp7 rabbits.

Effect of high voltage stimulation on blood flow in the rat hind limb.

The purpose of this study was to test the effect of high voltage stimulation (HVS) on blood flow velocity (BFV) in the rat hind limb. A 20-MHz pulsed Doppler device was used to measure BFV changes in the femoral artery of 20 anesthetized rats after electrical stimulation. The animals were stimulated under the following conditions: four different pulse rates, changes in stimulus voltage, and changes in polarity. Blood flow velocity also was measured in the unstimulated hind limb. Although each of the four pulse rates caused significant increases in BFV, the 20-pulse-per-second rate produced BFV increases significantly greater than the other three pulse rates. The BFV changes, on the average, occurred less than 1 minute from the onset of stimulation and lasted up to 14 minutes after the cessation of the stimulation. The BFV increased with increases in voltage intensity. Both the positive and negative poles elicited significant increases in BFV, but the negative pole produced the greatest increases. Blood flow in the unstimulated hind limb was unchanged after stimulation. This study indicates that HVS of muscle does cause significant increases in blood flow to the stimulated rat hind limb.

Post-mortem processing of export beef in Costa Rica

Eighteen intact male beef animals of 2 1 2 to 3 years of age, weighing 400–425 kg and fed entirely on rangelands grass, were slaughtered in a Costa Rican export plant. Six animals each were assigned to: low-voltage stimulation (75V), high-voltage stimulation (350V) and control. Hot-boning coupled with various chilling rates was also investigated. Mean muscle pH values for all treatment groups were above 6·4 at 1 1 2 h after slaughter, which may be related to the fact the animals were intact males which had been exposed to stressful conditions prior to slaughter. Palatability traits measured were tenderness, juiciness, flavor and overall desirability. With the exception of tenderness, there were no significant differences among electrical stimulation or chill treatments, and there were no interactions. The low-voltage electrical-stimulation treatment produced less tender meat ( P<0·05) than the high-voltage treatment, but there was no significant difference compared to the control. In an attempt to explain the finding that electrical stimulation had little or no effect on tenderness, the data were inspected in regard to ultimate pH. The panel score for samples with an ultimate pH less than 6 was 3·27, and for samples with a pH higher than 6 it was 5·70. A possible explanation is to suggest that the high-pH group underwent appreciable neutral proteolytic enzyme activity compared to the low-pH group.

Torque Production in Human Upper and Lower Limb Muscles with Voluntary and Electrically Stimulated Contractions

Two studies are reported in which the elbow flexor and extensor muscle groups and the quadriceps femoris muscle group in fifteen normal female subjects were tested under voluntary and electrically stimulated conditions. The torque produced during a maximum voluntary contraction (MVC) at each of six pre-determined joint angles was compared to the torque produced in maximum tolerated contractions (MTC) by two types of electrical stimulation (conventional interferential and high voltage stimulation). Results indicated a significant difference (p < 0.01) between the mean torque values produced by the MVC at all angles tested compared to the MTC. At the most favourable angle for producing an MTC, a mean torque of between 45 and 55% of an MVC for the elbow flexor and extensor muscles, and 65 to 74% for the quadriceps femoris muscle may be expected from both the high voltage and interferential stimulators.

Commentary

Appreciating the lack of experimental support behind the growing clinical use of high voltage stimulation (HVS), the authors have admirably set out to assess this relatively new treatment modality. Their study, including a control group, has focused on the comparative effectiveness of isometric exercise versus HVS for increasing the quadriceps muscle strength of healthy women. Although similar experimental models have been used to determine strengthening effects produced by electrical stimulation,1,2 no previous investigation has used HVS.

Post-mortem glycolysis in rabbit Longissimus dorsi muscles following electrical stimulation

The effects of both high voltage and low voltage electrical stimulation were studied in rabbit Longissimus dorsi muscles. The rate of fall of pH as well as the activities of phosphorylase a, phosphorylase kinase, and phosphorylase phosphatase were measured. The effects on the yield, ATPase activities, and calcium permeability of the sarcoplasmic reticulum (SR) were also measured. Although only high voltage stimulation increased the post-stimulation rate of pH fall, both types of electrical stimulation increased the phosphorylase a activity, apparently by increasing the activity of phosphorylase kinase and destroying a large part of the phosphorylase phosphatase activity. Electrical stimulation reduced the yield of SR and increased its basal ATPase activity. It also increased the ability of the SR to retain accumulated calcium. We conclude that the different rates of pH fall observed following the two types of stimulation are due to the differential effects of these treatments on one of the ATPase activities, probably the myofibrillar ATPase.