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PubMed1998

Electrical stimulation of cardiac tissue by a bipolar electrode in a conductive bath.

A three-dimensional (3-D) computer simulation of the electrical stimulation of passive cardiac tissue from a bipolar electrode placed within a conductive bath is presented. Through the bidomain model, the syncytial and anisotropic properties of cardiac tissue are taken into account; tissues with equal anisotropy and no transverse coupling are also considered. The membrane is represented by a capacitor and passive resistor in parallel. Located within an isotropic bath, the bipolar electrode is oriented either perpendicular or parallel to the tissue surface. For anisotropic tissue with a small cathode-tissue separation, the tissue surface is highly depolarized under the cathode with the depolarization persisting a considerable distance from the electrode in the transverse fiber direction. Adjacent to this region in the longitudinal direction, areas of hyperpolarization exist. At large distances from the cathode, the tissue surface is hyperpolarized in all directions when the electrode axis is perpendicular to the tissue. In the parallel case, surface depolarization creates buried regions of hyperpolarization. For the perpendicular configuration, the ratio of the steady-state maximum depolarization to steady-state maximum hyperpolarization, an estimate of the ratio of anodal to cathodal threshold, decreases rapidly with increasing cathode-tissue separation. In the parallel case, the depth of the conductive bath significantly affected the transmembrane potential distribution in the tissue. The use of a 3-D model more realistically simulates real-life electrical stimulation (such as stimulation with an implantable pacemaker) and provides insight into the effect of the volume conductor adjacent to the tissue.

Algorithms↗
PubMed2006

Anticonvulsant effects of transcranial direct-current stimulation (tDCS) in the rat cortical ramp model of focal epilepsy.

PURPOSE: Weak direct currents induce lasting alterations of cortical excitability in animals and humans, which are controlled by polarity, duration of stimulation, and current strength applied. To evaluate its anticonvulsant potential, transcranial direct current stimulation (tDCS) was tested in a modified cortical ramp-stimulation model of focal epilepsy. METHODS: The threshold for localized seizure activity (TLS) was determined in freely moving rats by applying a single train of rising bipolar pulses through a unilateral epicranial electrode. After tDCS, TLS was determined repeatedly for 120 min at intervals of 15 min. The first group of animals received two sessions of cathodal tDCS at 100 microA, one for 30 and one for 60 min. A third session consisted of 60 min of anodal tDCS. A second group received cathodal tDCS at 200 microA for 15 and for 30 min, as well as anodal tDCS for 30 min. RESULTS: Sixty minutes of cathodal tDCS at 100 microA resulted in a TLS increase lasting for >or=2 h. When the intensity was increased to 200 microA, a similar lasting TLS elevation occurred after a stimulation of just 30-min duration. In contrast, anodal tDCS at identical stimulation durations and current strengths had no significant effect on TLS. CONCLUSIONS: The anticonvulsive effect induced by cathodal tDCS depends on stimulation duration and current strength and may be associated with the induction of alterations of cortical excitability that outlast the actual stimulation. The results lead to the reasonable assumption that cathodal tDCS could evolve as a therapeutic tool in drug-refractory partial epilepsy.

Animals↗
PubMed1990

Monophasic versus biphasic cardiac stimulation: mechanism of decreased energy requirements.

The purpose of the present study was to examine the effects of monophasic and biphasic stimulation under conditions of full and incomplete repolarization in an in vivo dog model and in an in vitro rabbit ventricular single cell model. Strength-interval curves were constructed with monophasic cathodal stimulation and biphasic subthreshold anodal followed by cathodal stimulation in dogs prior to and late after left anterior descending coronary artery occlusion. At the monophasic absolute refractory period plus 10 msec, less cathodal current was required for biphasic compared to monophasic stimulation (P = 0.04). Moreover, the biphasic absolute ventricular refractory period (116 +/- 8 msec) was significantly shorter than the monophasic absolute ventricular refractory period (136 +/- 15 msec) (P less than 0.02). At coupling intervals greater than 30 msec after the monophasic absolute ventricular refractory period, there was no distinction between monophasic and biphasic stimuli. Similarly enhanced excitability was observed with biphasic stimuli in infarcted hearts. Voltage clamp measurements mimicking conditions of the in vivo studies demonstrated that when repolarization is incomplete, a hyperpolarizing prepulse reactivates additional sodium current resulting in enhanced excitability. In conclusion, biphasic stimulation consisting of a hyperpolarizing anodal prepulse followed by a cathodal pulse decreases the current required for excitation compared to cathodal monophasic stimulation in a critical zone near the ventricular absolute refractory period.

Animals↗
PubMed1994

Optical recordings of ventricular excitability of frog heart by an extracellular stimulating point electrode.

To enhance understanding of the excitability of cardiac muscle during rest, an optical technique using the fluorescent voltage sensitive dye di-4-ANEPPS was used. Unlike conventional electrical recordings, optical recordings are free from electrical artifacts and, therefore, allow the observation of the transmembrane potential not only following the stimulation pulse, but also during the pulse itself. Transmembrane potentials (Vm) were recorded optically from frog ventricular epicardium in calcium containing Ringer's solution directly under an extracellular stimulating point electrode. Anodal and cathodal S1 stimuli were applied at rest. As observed by previous investigators, the post-pulse excitatory responses for cathodal pulses, compared with anodal pulses were greater. Changes in transmembrane potential (delta Vm) during the pulse were as expected for a passive cable only for low intensity pulses (< 4 x the cathodal threshold of excitation in diastole, CTE). However, at the higher intensities necessary to produce an excitatory response (> 6-8 x CTE), an "irregular" response in Vm was observed--a reversal of the hyperpolarization during an anodal stimulus pulse and a reversal of the depolarization during a cathodal stimulus pulse. To elucidate further the biophysical basis for this behavior, delta Vm was mapped around the stimulating electrode. During stimulation, regions could be observed having a response with opposite polarity to that under the electrode (i.e., depolarization for an anodal pulse and hyperpolarization for a cathodal pulse). Removal of the bath solution or the addition of channel blockers did not eliminate the occurrence of these regions. These regions appear to be the basis for the irregular behavior of delta Vm directly under the electrode as well as for anodal excitation.

Animals↗
PubMed1999

Optimized pulse durations minimize the effect of polarity reversal on defibrillation efficacy with biphasic shocks.

There are conflicting results on the effect of polarity change on the defibrillation efficacy of biphasic shocks possibly caused by different shock durations. The goal of the present study was to investigate the influence of polarity reversal on defibrillation efficacy for different biphasic shock durations in a porcine animal model. In eight anesthesized pigs using a transvenous/submuscular lead system DFTs for 4 phase 1 durations were determined: 8.1 ms, 6 ms, 3.8 ms and 1.7 ms. The phase 1/phase 2 ratio was constant at 60%/40%. For cathodal shocks, the defibrillation coil in the right ventricular apex was the cathode during phase 1 and for anodal shocks it was the anode. For both polarities, the strength-duration curve revealed a DFT minimum at 3.8 ms (cathodal shocks: 21.3 +/- 6.4 J, P < 0.001; anodal shocks: 21.9 +/- 8 J, P = 0.05). For anodal shocks and phase 1 durations of 1.7, 3.8, and 6 ms there was no significant difference of the stored energy at the DFT compared to cathodal shocks. In contrast, significantly lower DFTs were observed for anodal shocks with a phase 1 duration of 8.1 ms (28.8 +/- 6.4 J compared to 33.1 +/- 5.9 J for cathodal shocks, P = 0.006). The effect of lower defibrillation energy requirements with polarity reversal depends on the total biphasic shock duration; for the pulse duration with the lowest DFT, polarity reversal does not increase defibrillation efficacy of biphasic shocks.

Animals↗
PubMed1994

Transvenous-subcutaneous defibrillation leads: effect of transvenous electrode polarity on defibrillation threshold.

INTRODUCTION: The defibrillation threshold (DFT) of a transvenous-subcutaneous electrode configuration is sometimes unacceptably high. To obtain a DFT with a sufficient safety margin, the defibrillation field can be modified by repositioning the electrodes or more easily by a change of electrode polarity. In a prospective randomized cross-over study, the effect of transvenous electrode polarity on DFT was evaluated. METHODS AND RESULTS: In 21 patients receiving transvenous-subcutaneous defibrillation leads, the DFT was determined intraoperatively for two electrode configurations. Two monophasic defibrillation pulses were delivered in sequential mode between either the right ventricular (RV) electrode as common cathode and the superior vena cava (SVC) and subcutaneous electrodes as anodes (configuration I) or the SVC electrode as common cathode and the RV and subcutaneous electrodes as anodes (configuration II). In each patient, both electrode configurations were used alternately with declining energies (25, 15, 10, 5, 2 J) until failure of defibrillation occurred. The DFT did not differ between both configurations (18.3 +/- 8.2 J vs 18.9 +/- 8.9 J; P = 0.72). Eleven patients had the same DFT with both electrode configurations, 5 patients a lower DFT with the RV electrode as cathode, and 5 patients a lower DFT with the SVC as cathode. Four patients had a sufficiently low DFT (< or = 25 J) with only 1 of the 2 configurations. CONCLUSION: A change of electrode polarity of transvenous-subcutaneous defibrillation electrodes may result in effective defibrillation if the first electrode polarity tested fails to defibrillate. In general, neither the RV electrode nor the SVC electrode is superior if used as a common cathode in combination with a subcutaneous anodal chest patch.

Adult↗
PubMed2000

Micropatterning of organic electronic devices by cold-welding

A simple and general postdeposition electrode patterning technique for active organic electronic devices is demonstrated and is applied to patterning the metal cathodes of organic light-emitting devices. Selective lift-off of the metal cathode layer is achieved by pressing a prepatterned, metal-coated silicon stamp on the unpatterned device layers. Under pressure, the metal coating on the stamp cold-welds to the metal cathode coating the underlying organic films. Subsequent separation of the stamp from the substrate results in removal of the cathode metal in the regions contacted by the stamp, resulting in submicrometer feature definition. A 17x17 passive matrix display, with a pixel size of 440 micrometers by 320 micrometers, was fabricated with this process. Cold-welding followed by lift-off of the cathode metal allows simple, cost-effective, and high-throughput large-area fabrication of organic electronic devices.

Journal Article↗
PubMed2006

Latency and initiation of the human vestibuloocular reflex to pulsed galvanic stimulation.

Cathodal galvanic currents activate primary vestibular afferents, whereas anodal currents inhibit them. Pulsed galvanic vestibular stimulation (GVS) was used to determine the latency and initiation of the human vestibuloocular reflex. Three-dimensional galvanic vestibuloocular reflex (g-VOR) was recorded with binocular dual-search coils in response to a bilateral bipolar 100-ms rectangular pulse of current at 0.9 (near-threshold), 2.5, 5.0, 7.5, and 10.0 mA in 11 normal subjects. The g-VOR consisted of three components: conjugate torsional eye rotation away from cathode toward anode; vertical divergence (skew deviation) with hypertropia of the eye on the cathodal and hypotropia of the eye on the anodal sides; and conjugate horizontal eye rotation away from cathode toward anode. The g-VOR was repeatable across all subjects, its magnitude a linear function of the current intensity, its latency about 9.0 ms with GVS of >or=2.5 mA, and was not suppressed by visual fixation. At 10-mA stimulation, the g-VOR [x, y, z] on the cathodal side was [0.77 +/- 0.10, -0.05 +/- 0.05, -0.18 +/- 0.06 degrees ] (mean +/- 95% confidence intervals) and on the anodal side was [0.79 +/- 0.10, 0.16 +/- 0.05, -0.19 +/- 0.06 degrees ], with a vertical divergence of 0.20 degrees . Although the horizontal g-VOR could have arisen from activation of the horizontal semicircular canal afferents, the vertical-torsional g-VOR resembled the vestibuloocular reflex in response to roll-plane head rotation about an Earth-horizontal axis and might be a result of both vertical semicircular canal and otolith afferent activations. Pulsed GVS is a promising technique to investigate latency and initiation of the human vestibuloocular reflex because it does not require a large mechanical apparatus nor does it pose problems of head inertia or slippage.

Adult↗
PubMedDate not supplied

Effects of direct current electric fields on cell migration and actin filament distribution in bovine vascular endothelial cells.

Electric fields exceeding 1 V/cm occur during wound healing, morphogenesis, and tumor growth, and such fields have been shown to induce directional migration of a variety of different cells. However, the mechanism by which electric fields direct cell movement is not yet understood, and the effects on vascular endothelial cells are entirely unknown. We demonstrate that cultured bovine aortic endothelial cells migrate toward the cathode of an applied electric field. Time-lapse microscopic imaging shows that the field suppresses protrusive activity from anode-facing surfaces of the cells while stimulating protrusions from surfaces that face the cathode. The threshold for this response is 1-2 V/cm, similar to field strengths measured in vivo. In addition, fluorescence microscopy shows that lamellipodia projecting toward the cathode are rich in actin filaments. Using quantitative image analysis, we show that the electric field induces a transient 80% increase in the amount of filamentous actin in the cell. Comparison of the distribution of F-actin with total protein distribution indicates that F-actin is asymmetrically distributed in the cytoplasm, being selectively enriched toward the cathode. We propose that physiological electric fields direct cell migration by eliciting an intracellular signal that creates new sites for actin assembly in the cathodal cytoplasm.

Actins↗
PubMed1978

Sequential unipolar strength-interval curves and conduction times during myocardial ischemia and reperfusion in the dog.

Computerized techniques were employed to generate alternating anodal and cathodal or sequential anodal strength-interval curves during and following 15-minute coronary artery ligations in 14 anesthetized dogs. The right atrium was paced at 2.5 Hz, and unipolar ventricular strength-interval curves with simultaneous conduction times were recorded every 45-120 seconds during ischemia and reperfusion. Within 1--2 minutes of ligation, anodal midcurve and late diastolic thresholds fell sharply, and cathodal thresholds fell slightly or changed little. After 5 minutes of ischemia, anodal thresholds remained low, cathodal thresholds rose, and conduction times increased. At 10--15 minutes of ligation, if the ischemic zone was small, anodal thresholds were low, often approaching cathodal values, and conduction returned toward control values. When the ischemic zone was large, unipolar thresholds and conduction times increased late during the ligation period. Throughout the course of ischemia, the falling limb of the strength-interval curve shifted progressively to the left indicating shorter refractory periods. Following abrupt reperfusion, anodal phase 3 dips promptly reappeared; refractory periods returned toward control, and supernormal conduction was noted. By 3--5 minutes of reperfusion, the falling limb of the strength-interval curve had shifted to the right of control and conduction times increased. Thus, vulnerability to arrhythmias during early ischemia (i.e., 5 minutes) is characterized by low anodal midcurves and late diastolic thresholds, short refractory periods, and slow conduction. During the first minute of reperfusion, anodal excitability is increased during the early dip and conduction times are supernormal. Increases in anodal excitability correlate better with the peak incidence of early ligation and reperfusion arrhythmias than do changes in cathodal excitability.

Animals↗
PubMed1993

Optical measurements of transmembrane potential changes during electric field stimulation of ventricular cells.

We evaluated transmembrane potential changes at the ends of isolated rabbit ventricular myocytes during defibrillation-strength shocks given in the cellular refractory period. The myocytes were stimulated (S1 pulse) to produce an action potential. Then a constant-field shock (S2 pulse) with an electric field of 20 or 40 V/cm was given at an S1-S2 interval of 50 msec. The cells were stained with potentiometric dye (di-4-ANEPPS), and the cell end facing the S2 anode or cathode was illuminated with a laser while the fluorescence was recorded. During S2, the cell end facing the S2 cathode became more positive intracellularly, whereas the cell end facing the S2 anode became more negative intracellularly. The S2-induced transmembrane potential change at the cell end (delta Vm) was determined relative to the amplitude of the S1-induced action potential (APA) in each recording (i.e., delta Vm/APA). In Tyrode's solution containing 4.5 mM potassium, delta Vm/APA for 40-V/cm S2 was 1.36 +/- 0.34 at the cell end facing the S2 cathode and -1.65 +/- 0.61 at the cell end facing the S2 anode (n = 9). For the 20-V/cm S2, delta Vm/APA was 0.61 +/- 0.33 at the cell end facing the S2 cathode and -0.71 +/- 0.33 at the cell end facing the S2 anode (n = 6). The delta Vm/APA was not significantly influenced by 20 mM diacetyl monoxime. These results indicate that large delta Vm values occurred at the ends of the cells during S2. The calculated values of delta Vm, assuming a nominal APA of 130 mV, were 177 and -214 mV for the 40-V/cm S2 and 79 and -93 mV for the 20-V/cm S2. The delta Vm was correlated with cell size (r > or = 0.95) and agreed with values predicted by the S2 electric field strength multiplied by half of the cell length to within 27%. When the potassium concentration was increased to 20 mM, delta Vm/APA for 40 V/cm S2 increased 85% and 67% at the cell ends facing the S2 cathode and anode, respectively (n = 9, p < 0.005 versus 4.5 mM potassium), consistent with reduced APA. Thus, with normal or elevated extracellular potassium, transmembrane potential changes at the ends of cells during defibrillation-type stimulation are large enough to produce activation or recovery of voltage-dependent ion channels and may produce the effects responsible for defibrillation.

Animals↗
PubMed2006

Temporally and spatially coordinated roles for Rho, Rac, Cdc42 and their effectors in growth cone guidance by a physiological electric field.

Although it is known that neuronal growth cones migrate towards the cathode of an applied direct current (DC) electric field (EF), resembling the EF present in the developing nervous system, the underlying mechanism remains unclear. Here, we demonstrate temporally and spatially coordinated roles for the GTPases Rac, Cdc42 and Rho and their effectors. Growth cones of cultured Xenopus embryonic spinal neurons turned towards the cathode but collective inhibition of Rho, Rac and Cdc42 attenuated turning. Selective inhibition of Rho, Cdc42 or Rac signalling revealed temporally distinct roles in steering by an electrical gradient. Rho, Rac and Cdc42 are each essential for turning within the initial 2 hours (early phase). Later, Rho and Cdc42 signals remain important but Rac signalling dominates. The EF increased Rho immunofluorescence anodally. This correlated spatially with collapsed growth cone morphology and reduced anodal migration rates, which were restored by Rho inhibition. These data suggest that anodally increased Rho activity induces local cytoskeletal collapse, biasing growth cone advance cathodally. Collapse might be mediated by the Rho effectors p160 Rho kinase and myosin light chain kinase since their inhibition attenuated early turning. Inhibitors of phosphoinositide 3-kinase, MEK1/2 or p38 mitogen-activated protein kinase (MAPK) did not affect turning behaviour, eliminating them mechanistically. We propose a mechanism whereby Rac and Cdc42 activities dominate cathodally and Rho activity dominates anodally to steer growth cones towards the cathode. The interaction between Rho GTPases, the cytoskeleton and growth cone dynamics is explored in the companion paper published in this issue. Our results complement studies of growth cone guidance by diffusible chemical gradients and suggest that growth cones might interpret these co-existing guidance cues selectively.

Animals↗
PubMed1981

Responses of rat chorda tympani fibers to electrical stimulation of the tongue.

Responses of rat chorda tympani fibers to stimulations of the tongue with linearly rising anodal currents of varying rise rates and intensities, cathodal currents and chemical solutions representing the four basic taste qualities were obtained. Single fibers were classified into four types according to their response patterns to anodal and cathodal current stimulations of the tongue. Type A1 fibers responded only to an anodal current with both transient and steady response phases. Type A2 fibers responded only to an anodal current with only a steady response phase. Type B fibers responded to both anodal and cathodal currents. Type C fibers responded only to a cathodal current. Sensitivity to the rate f anodal current rise varied widely among individual chorda tympani fibers. The NaCl-sensitive fibers were most sensitive, the tartaric acid-sensitive fibers next, and the sucrose-sensitive fibers least. Fibers responding to cathodal current were sensitive to quinine hydrochloride. Fibers which showed rhythmic bursts of discharges in response to chemical stimuli also gave a similar discharge pattern in response to electrical stimulation.

Animals↗
PubMedDate not supplied

Anodal block: can this occur during routine nerve conduction studies?

The median nerves of five normal subjects were electrically excited at the wrist with fine-tipped stimulating electrodes in a bipolar fashion. Compound sensory nerve action potentials (CSNAPs) were recorded from the index finger and compound muscle action potentials (CMAPs) from the thenar muscles. Both the cathode and the anode were positioned over the length of the nerve. Recordings were performed with different cathode-to-anode distances of 5, 10, 20, and in some cases, 30 mm. Just supramaximal CSNAPs and CMAPs were obtained initially with the cathode situated distal to the anode and then with the stimulus polarity reversed. There were no significant differences in the amplitude, duration, and morphology of the CSNAPs or CMAPs that were recorded by using different stimulus polarities. There was a consistent increase in the onset latency of the responses when the stimulus polarity was reversed (cathode located proximal to anode). This increase in latency was proportionate to the increase in distance from the cathode to the recording electrode. The effect of anodal block could not be observed from the above experiment.

Action Potentials↗
PubMed2005

[Effects of surface potentials of tooth hard tissue on bone remodeling in rabbit tibiae].

OBJECTIVE: To investigate the influence of surface potentials of tooth hard tissue on bone remodeling. METHODS: After insured the surface potentials of human extracted teeth with electrochemical methods, teeth sections and artificial hydroxyapatite were implanted into 25 rabbits' tibiae. The rabbits were sacrificed at 1, 2, 4, 6 and 8 weeks after implantation, respectively. The bone regeneration was compared between opposite two sides (cathode side and anode side) of tooth sections using hematoxylin-eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) activity detecting and tetracycline tracing method. RESULTS: Resorption lacunae was seen in the tibiae facing to the enamel anode and new bone density in the implant bed near the cathode of tooth samples was much higher than that near the anode, while the number of TRAP positive cells near the cathode was smaller than that near the anode (P < 0.01). The fluorescent area of tetracycline tracing near the cathode was larger than that near the anode (P < 0.05). CONCLUSIONS: The cathode of tooth hard tissue (cementum) could improve or trigger new bone formation, while the other side, anode (enamel), could improve the bone resorption. This study suggests that tooth hard tissue's electrochemical characteristic might affect the remodeling of alveolar bone, and tooth supraeruption and the alveolar bone loss after tooth extraction might result from the redundant or lack of root electrochemical stimulation to bone.

Alveolar Bone Loss↗
PubMed1989

[A method of electrical cervical motor root stimulation: effect of stimulation parameters and normal values].

Following percutaneous stimulation over the cervical column, a compound action potential (CMAP) can be recorded from the muscles of the arm. The actual site of excitation is located on the spinal motor roots, probably near to their exit from the spinal column. This method allows the electroneurographical assessment of the proximal brachial plexus and is used to calculate a central motor conduction time following motor cortex stimulation. So far, the optimal placement of the stimulating electrodes is unknown, and normal values must be established. We measured onset latencies of CMAPs of Mm biceps brachii and abductor digiti minimi (ADM) after supramaximal cervical motor root stimulation in 31 healthy subjects. Distances between the stimulating electrodes varying from 3 to 12 cm were studied. With 6 cm interelectrode distance, the electrodes were then placed either in a longitudinal or in a transversal direction, with the cathode over the interspace C7/T1 or C6/7. In addition, for the longitudinal stimulation, the effect of cathodal versus anodal stimulation over the C7/T1 interspace was studied. The results of various stimulating electrode positions and directions over the lower cervical column were then compared statistically. With the longitudinal electrode position, the cathode over C7/T1 and the anode placed 6 cm cranially, it was always possible to excite muscles from both sides simultaneously. When a very proximal stimulation site at the nerve roots was required in both muscles after one single stimulus, this method was superior to the transversal electrode position with the cathode C6/7 or C7/T1, or to the longitudinal electrode position with the anode over C7/T1 and the cathode placed cranially. For the ADM (29 subjects, 58 sides), the mean onset latency was 13.795 +/- 1.307 ms (mean +/- 1 SD), the mean side-to-side difference (SSD) was 0.452 +/- 0.388 ms. The mean amplitude was 7.71 +/- 2.64 mV, the mean side-to-side quotient (SDQ) was 41.88 +/- 97.59%. For M. biceps (29 subjects, 58 sides), the mean onset latency was 5.138 +/- 0.582 ms, the mean SSD 0.166 +/- 0.193 ms. The mean amplitude was 7.91 +/- 3.45 mV, the mean SSQ was 55.42 +/- 67.94%.

Adult↗
PubMed1989

[Nonthoracotomy internal defibrillation in dogs using a body surface electrode with a transvenous catheter electrode].

The efficacy of truncated exponential waveform shocks using a cardioverter-defibrillator catheter (Medtronic 6880) and body surface electrodes was examined in comparison with using a RV epicardial patch electrode and a LV epicardial patch electrode in fifteen pentobarbital-anesthetized dogs. The defibrillation thresholds (DFT) for 5 lead configurations were measured by the total energy, peak voltage and peak current: A) a body surface electrode (positioned at the right lateral chest wall) as the anode and a body surface electrode (positioned at the left lateral chest wall) as the cathode; B) a superior vena cava catheter electrode as the anode and a RV apex catheter electrode as the cathode; C1) a body surface electrode (positioned at left anterior chest wall) as the anode and a RV apex catheter electrode as the cathode; C2) a body surface electrode (positioned at the left lateral chest wall) as the anode and a RV apex catheter electrode as the cathode; and D) a RV epicardial patch electrode as the anode and a LV epicardial patch electrode as the cathode. The total energy at DFT for configurations C2 and D was lower than for configurations A, B, and C1, respectively (7.2 +/- 3.1 and 4.7 +/- 2.0 less than 18.9 +/- 3.8, 12.0 +/- 3.8 and 11.2 +/- 2.2 joules; p less than 0.05). The peak voltage at DFT for configurations C2 and D was lower than for configurations A, B, and C1, respectively (463 +/- 70 and 377 +/- 73 less than 767 +/- 85, 585 +/- 117 and 600 +/- 62 volts; P less than 0.05).

Animals↗
PubMed1980

Apparent mitochondrial creatine kinase in the serum of a patient with metastatic cancer to the liver.

Creatine kinase (CK, EC 2.7.3.2) activity in the serum of a patient with metastatic carcinoma migrated as two distinct bands cathodal to the origin and to CK-3 on agarose gel electrophoresis. The more cathodal isoenzyme (CKm-2) is of high molecular mass, is precipitated by ammonium sulfate at 30% of saturation, and is not retarded by Sephadex G-100. Treatment with urea at a concentration of 6 mol/L caused CKm-2 to elute with proteins of lower molecular mass on a G-100 column and shifted the electrophoretic migration to a position just cathodal to the origin (CKm-1). Antibody to CK-1 and CK-2 did not affect the activity of either CKm-1 or CKm-2. Similarities between these cathodal bands of CK activity and mitochondrial CK suggest the mitochondrial origin of these isoenzymes. These cathodal CK isoenzymes reacted unpredictably with different commercial reagent systems for determination of CK activity in serum or in agarose gel.

Clinical Enzyme Tests↗