Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.
The output neurons of the cerebellar cortex.
An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.
3 beta,5,14-Trihydroxy-19-oxo-5 beta-card-20(22)-enolide. The aglycone cardioactive agent isolated from Strophanthus Kombe, S. gratus and other species; it is a very toxic material formerly used as digitalis. Synonyms: Apocymarin; Corchorin; Cynotoxin; Corchorgenin.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.
Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.
The superficial GRAY MATTER of the CEREBELLUM. It consists of two main layers, the stratum moleculare and the stratum granulosum.
A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The remnants of plant cell walls that are resistant to digestion by the alimentary enzymes of man. It comprises various polysaccharides and lignins.
Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.
The hollow, muscular organ that maintains the circulation of the blood.
A surface anesthetic that acts by preventing transmission of impulses along NERVE FIBERS and at NERVE ENDINGS.
A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.
Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.
A dihydropyridine calcium channel antagonist that acts as a potent arterial vasodilator and antihypertensive agent. It is also effective in patients with cardiac failure and angina.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Use of electric potential or currents to elicit biological responses.
Glycosides from plants of the genus DIGITALIS. Some of these are useful as cardiotonic and anti-arrhythmia agents. Included also are semi-synthetic derivatives of the naturally occurring glycosides. The term has sometimes been used more broadly to include all CARDIAC GLYCOSIDES, but here is restricted to those related to Digitalis.
The hemodynamic and electrophysiological action of the HEART VENTRICLES.
Contractile activity of the MYOCARDIUM.
The species Balaenoptera acutorostrata, in the family Balaenopteridae. It is the smallest of the WHALES in the family and though mainly oceanic, is often found in coastal waters including bays and estuaries.
The ability of a substrate to allow the passage of ELECTRONS.
Mice which carry mutant genes for neurologic defects or abnormalities.
Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.
Coronary vasodilator that is an analog of iproveratril (VERAPAMIL) with one more methoxy group on the benzene ring.
Long, pliable, cohesive natural or manufactured filaments of various lengths. They form the structure of some minerals. The medical significance lies in their potential ability to cause various types of PNEUMOCONIOSIS (e.g., ASBESTOSIS) after occupational or environmental exposure. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p708)
Elements of limited time intervals, contributing to particular results or situations.
The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.
A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.
The innermost layer of the heart, comprised of endothelial cells.
Cyclopentanophenanthrenes with a 5- or 6-membered lactone ring attached at the 17-position and SUGARS attached at the 3-position. Plants they come from have long been used in congestive heart failure. They increase the force of cardiac contraction without significantly affecting other parameters, but are very toxic at larger doses. Their mechanism of action usually involves inhibition of the NA(+)-K(+)-EXCHANGING ATPASE and they are often used in cell biological studies for that purpose.
An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.
Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.
Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.
1,4-Diethylene dioxides. Industrial solvents. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), dioxane itself may "reasonably be anticipated to be a carcinogen." (Merck Index, 11th ed)
An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.
Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.
A TEXTILE fiber obtained from the pappus (outside the SEEDS) of cotton plant (GOSSYPIUM). Inhalation of cotton fiber dust over a prolonged period can result in BYSSINOSIS.
A photoprotein isolated from the bioluminescent jellyfish Aequorea. It emits visible light by an intramolecular reaction when a trace amount of calcium ion is added. The light-emitting moiety in the bioluminescence reaction is believed to be 2-amino-3-benzyl-5-(p-hydroxyphenyl)pyrazine (AF-350).
Small band of specialized CARDIAC MUSCLE fibers that originates in the ATRIOVENTRICULAR NODE and extends into the membranous part of the interventricular septum. The bundle of His, consisting of the left and the right bundle branches, conducts the electrical impulses to the HEART VENTRICLES in generation of MYOCARDIAL CONTRACTION.
Insulated enclosures in which temperature, humidity, and other environmental conditions can be regulated at levels optimal for growth, hatching, reproduction, or metabolic reactions.
The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.
A sulphonylurea hypoglycemic agent with actions and uses similar to those of CHLORPROPAMIDE.
Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.
A group comprised of several species of eared seals found in two genera, in the family Otariidae. In comparison to SEA LIONS, they have an especially dense wooly undercoat.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
Pyridines substituted in any position with an amino group. May be hydrogenated, but must retain at least one double bond.
The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).
Inorganic compounds that contain barium as an integral part of the molecule.
A class I anti-arrhythmic agent (one that interferes directly with the depolarization of the cardiac membrane and thus serves as a membrane-stabilizing agent) with a depressant action on the heart similar to that of guanidine. It also possesses some anticholinergic and local anesthetic properties.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.
A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)
Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.
A class Ia antiarrhythmic drug that is structurally-related to PROCAINE.
A sulfonylurea hypoglycemic agent that is metabolized in the liver to 1-hydrohexamide.
Four clusters of neurons located deep within the WHITE MATTER of the CEREBELLUM, which are the nucleus dentatus, nucleus emboliformis, nucleus globosus, and nucleus fastigii.
A part of the MEDULLA OBLONGATA situated in the olivary body. It is involved with motor control and is a major source of sensory input to the CEREBELLUM.
An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
The rate dynamics in chemical or physical systems.
A highly poisonous compound that is an inhibitor of many metabolic processes and is used as a test reagent for the function of chemoreceptors. It is also used in many industrial processes.
Antiarrhythmic agent pharmacologically similar to LIDOCAINE. It may have some anticonvulsant properties.
A benzoate-cevane found in VERATRUM and Schoenocaulon. It activates SODIUM CHANNELS to stay open longer than normal.
Bundles of actin filaments (ACTIN CYTOSKELETON) and myosin-II that span across the cell attaching to the cell membrane at FOCAL ADHESIONS and to the network of INTERMEDIATE FILAMENTS that surrounds the nucleus.
The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.
An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
A calcium channel blocker that is a class IV anti-arrhythmia agent.
Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or PERIPHERAL NERVE DISEASES. Motor ataxia may be associated with CEREBELLAR DISEASES; CEREBRAL CORTEX diseases; THALAMIC DISEASES; BASAL GANGLIA DISEASES; injury to the RED NUCLEUS; and other conditions.

Automatic activity in depolarized guinea pig ventricular myocardium. Characteristics and mechanisms. (1/635)

Membrane potential was changed uniformly in segments, 0.7-1.0 mm long, of guinea pig papillary muscles excised from the right ventricle by using extracellular polarizing current pulses applied across two electrically insulated cf preparations superfused with Tyrode's solution at maximum diastolic membrane potentials ranging from-35.2+/-7.5 (threshold) to +4.0+/-9.2 mV. The average maximum dV/dt of RAD ranged from 17.1 to 18.0 V/sec within a membrane potential range of -40 to +20 mV. Raising extracellular Ca2+ concentration [Ca2+]0 from 1.8 to 6.8 mM, or application of isoproterenol (10(-6)g/ml) enhanced the rate of RAD, but lowering [Ca2+]0 to 0.4 mM or exposure to MnCl2 (6 mM) abolished RAD. RAD were enhanced by lowering extracellular K+ concentration [K+]0 from 5.4 to 1.5 mM. RAD were suppressed in 40% of fibers by raising [K+]0 to 15.4 mM, and in all fibers by raising [K+]0 to 40.4 mM. This suppression was due to increased [K+]0 and not to K-induced depolarization because it persisted when membrane potential was held by means of a conditioning hyperpolarizing puled gradually after maximum repolarization. These observations suggest that the development of RAD in depolarized myocardium is associated with a time-dependent decrease in outward current (probably K current) and with increase in the background inward current, presumably flowing through the slow cha-nel carrying Ca or Na ions, or both.  (+info)

Effect of electrotonic potentials on pacemaker activity of canine Purkinje fibers in relation to parasystole. (2/635)

Isolated false tendons excised form dog hearts were mounted in a three-chamber tissue bath. Isotonic sucrose solution was perfused in the central chamber to provide a region of depressed conductivity between the fiber segments in chambers 1 and 3, which were perfused with Tyrode's solution. The electrotonic influence of spontaneous or driven responses evoked in chamber 3 during the first half of the spontaneous cycle of a chamber 1 peacemaker delayed the next spontaneous discharge. This effect changed to acceleration when the chamber 3 segment fired during the second half of the spontaneous cycle. We found that subthreshold depolarizing current pulses 50-300 msec applied across the sucrose gap caused similar degrees of delay or acceleration. Furthermore, hyperpolarizing currents caused the reverse pattern. The results indicate that the discharge pattern of a parasystolic focus may be altered by the electrotonic influence of activity in the surrounding tissue. The significance of these findings is considered in relation to the mechanism of production of parasystolic rhythms.  (+info)

Hierarchy of ventricular pacemakers. (3/635)

To characterize the pattern of pacemaker dominance in the ventricular specialized conduction system (VSCS), escape ventricular pacemakers were localized and quantified in vivo and in virto, in normal hearts and in hearts 24 hours after myocardial infarction. Excape pacemaker foci were localized in vivo during vagally induced atrial arrest by means of electrograms recorded from the His bundle and proximal bundle branches and standard electrocardiographic limb leads. The VSCS was isolated using a modified Elizari preparation or preparations of each bundle branch. Peacemakers were located by extra- and intracellular recordings. Escape pacemaker foci in vivo were always in the proximal conduction system, usually the left bundle branch. The rate was 43+/-11 (mean+/-SD) beats/min. After beta-adrenergic blockade, the mean rate fell to 31+/-10 beats/min, but there were no shifts in pacemaker location. In the infarcted hearts, pacemakers were located in the peripheral left bundle branch. The mean rate was 146+/-20 beats/min. In isolated normal preparations, the dominant pacemakers usually were in the His bundle, firing at a mean rate of 43+/-10 beats/min. The rates of pacemakers diminished with distal progression. In infarcted hearts, the pacemakers invariably were in the infarct zone. The mean firing rates were not influenced by beta-adrenergic blockade. The results indicate that the dominant pacemakers are normally in the very proximal VSCS, but after myocardial infarction pacemaker dominance is shifted into the infarct. Distribution of pacemaker dominance is independent of sympathetic influence.  (+info)

Electrophysiological effects of mexiletine in man. (4/635)

The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node.  (+info)

Transient inward current underlying arrhythmogenic effects of cardiotonic steroids in Purkinje fibres. (5/635)

1. Voltage-clamp experiments were carried out in calf Purkinje fibres to determine the basis of transient depolarizations (TDs) associated with digitalis-induced arrhythmias. 2. Under the influence of strophanthidin, depolarizing clamp pulses were followed by a transient inward current (TI) which was small or absent in untreated preparations. The TI also appeared in the wake of a train of action potentials. 8. The TI can help generate spontaneous depolarizations in preparations showing the low voltage oscillations which often occur with advanced digitalis toxicity. 8. The TI can help generate spontaneous depolarizations in preparations showing the 'low voltage oscillation' which often occur with advanced digitais toxicity. It was designated TI because its magnitude and timing were appropriate to account for the TD. 3. Longitudinal voltage non-uniformity during the TI was determined with two voltage-recording micro-electrodes. Although the non-uniformity was not severe, the TI wave form was observed when the voltage difference signal was used to measure membrane current density. 4. Over the diastolic range of potential, the strophanthidin-induced TI appeared superimposed upon the normal pace-maker mechanism, the decay of a potassium current, iK2. The TI could be dissociated from iK2, however, by means of its unusual kinetic properties. 5. TIs could also be recorded at holding potentials positive to -55 mV, i.e. outside the range where iK2 deactivation occurs. 6. The TI amplitude showed a slow and strongly sigmoid dependence on the duration of the preceding depolarizing pulse. Stronger depolarizing reduced the TI amplitude, while slowing and exaggerating the sigmoid time-dependence. 7. Two clamp pulses in close succession gave additive effects in evoking a subsequent TI. This finding and the sigmoid time-dependence fit with previous observations that TDs are most prominent following a series of closely spaced action potentials.  (+info)

Significance of late diastolic potential preceding Purkinje potential in verapamil-sensitive idiopathic left ventricular tachycardia. (6/635)

BACKGROUND: Verapamil-sensitive idiopathic left ventricular tachycardia (VT) is due to reentry with an excitable gap. A late diastolic potential (LDP) is recorded during endocardial mapping of this VT, but its relation to the reentry circuit and significance in radiofrequency (RF) ablation remain to be elucidated. METHODS AND RESULTS: Sixteen consecutive patients with this specific VT were studied (12 men and 4 women; mean age, 32 years). In all patients, sustained VT was induced and during left ventricular endocardial mapping, LDP preceding Purkinje potential (PP) was recorded at the basal (11 patients), middle (3 patients), or apical septum (2 patients). The area with LDP recording was confined to a small region (0.5 to 1.0 cm2) in each patient and was included in the area where PP was recorded (2 to 3 cm2). The relative activation times of LDP, PP, and local ventricular potential (V) at the LDP recording site to the onset of QRS complex were -50.4+/-18.9, -15.2+/-9.6, and 3.0+/-13.3 ms, respectively. The earliest ventricular activation site during VT was identified at the posteroapical septum and was more apical in the septum than the region with LDP in every patient. In 9 patients, VT entrainment was done by pacing from the right ventricular outflow tract while recording LDP. During entrainment, LDP was orthodromically captured, and as the pacing rate was increased, the LDP-to-PP interval was prolonged, whereas stimulus-to-LDP and PP-to-V interval were constant. In 3 patients, the pressure applied to the catheter tip at the LDP region resulted in conduction block between LDP and PP and in VT termination. RF energy application at the LDP recording site successfully eliminated VT. CONCLUSIONS: LDP was suggested to represent the excitation at the entrance to the specialized area with a conduction delay in response to the increase in the rate within the critical slow conduction zone participating in the reentry circuit of this VT. LDP can be a useful marker for successful RF ablation for this VT.  (+info)

Effect of acetylstrophanthidin on action potential duration and relation with extracellular potassium in sheep isolated Purkinje fibers. (7/635)

AIM: To study the relation between the effect of acetylstrophanthidin on action potential duration (APD) and the extracellular potassium concentration. METHODS: Effect of acetylstrophanthidin (AS 0.15 mmol.L-1) on APD at different extracellular potassium concentrations was studied at the stimulation cycle lengths of 990 and 690 ms in sheep isolated cardiac Purkinje fibers using the standard microelectrode technique. RESULTS: At [K+]o 4.0 mmol.L-1, the biphasic effect of AS on APD appeared obviously. Both APD50 and APD90 were lengthened within the first 10 min of drug exposure. After 10 min, they were shortened at all pacing cycle lengths. On the other hand, at [K+]o 5.4 mmol.L-1, AS only shortened APD markedly without lengthening effect on it. The biphasic and monophasic effects of AS on APD were found at [K+]o 4.0 mmol.L-1 and 5.4 mmol.L-1, respectively. CONCLUSION: The effect of AS on APD was related to the concentration of [K+]o.  (+info)

Electrophysiological effects of LU111995 on canine hearts: in vivo and in vitro studies. (8/635)

We studied the electrophysiological effects of LU111995 (1-15 mg/kg p.o.) in conscious dogs with chronic atrioventricular block and ventricular pacing at 50 to 130 beats/min. LU111995 had no effects on idioventricular rhythm, QRS duration, and ventricular conduction time. It significantly prolonged Q-T interval (by 5-8%) and effective refractory period (ERP) (by 5-12%) with the maximal effect at 4 h after a 10 mg/kg dose. At 10 and 15 mg/kg, it increased the ERP/Q-T ratio. In vitro, the effects of LU111995 (1 x 10(-7) to 1 x 10(-5) M) on action potentials of Purkinje fibers (PFs) and M cells were studied at cycle lengths (CL) of 300 to 2000 ms. It had no effects on maximum diastolic potential and action potential amplitude in either tissue. High concentrations induced a moderate, rate-independent decrease of Vmax in M cells. In PFs and M cells, it produced reverse use-dependent lengthening of action potential duration (APD). In PFs at long CL, the drug exhibited a biphasic concentration-dependent effect on APD: maximum prolongation (by 26% at a CL of 2000 ms) was attained at 1 x 10(-6) M, and a decrease of APD occurred at higher concentrations. In M cells, the maximum effect on APD occurred at 3 x 10(-6) M. Early afterdepolarizations were seen in 50% of M cell preparations but only at CL of 2000 ms. Triggered activity did not occur. In summary, LU111995 prolongs the Q-T interval to a limited degree and is not arrhythmogenic over the physiological range of CLs.  (+info)

Changes in intracellular sodium ion activity (aiNa) produced by several cardiac glycosides were correlated with twitch tension in sheep cardiac Purkinje strands. Simultaneous measurements of aiNa and twitch tension were obtained through the use of Na-sensitive intracellular microelectrodes (ETH 227) in Purkinje preparations stimulated at a frequency of 1 Hz. All concentrations of ouabain, acetylstrophanthidin, and actodigin that were tested caused an increase in aiNa immediately before, or coincident with, a positive inotropic effect. No fall in aiNa was observed at any positive inotropic concentration of digitalis in these beating fibers. In all cases, the onset and washout of the positive inotropic effect were paralleled by the rise and fall in aiNa, respectively. No dissociation between changes in aiNa and twitch tension occurred at any concentration of any of the agents used. The relation between changes in aiNa and twitch tension was linear with 1 mM increase in aiNa producing about a 100% ...
We studied the relation of the maximal upstroke velocity (Vmax) of action potentials to the peak sodium current (INa) under voltage clamp in single, internally perfused, canine cardiac Purkinje cells under conditions that ensured membrane action potentials due only to INa. Three different methods of altering sodium channel availability were investigated: voltage-dependent inactivation, tetrodotoxin (TTX) block, and use-dependent block by quinidine. Under all three conditions, the relation of Vmax to INa was nonlinear, and no relation was found that would allow prediction of INa results from Vmax measurements. With voltage-dependent inactivation or TTX block, sodium channel availability measured by Vmax was reduced less than availability measured by peak INa, so that Vmax overestimated sodium channel availability. This overestimation of sodium channel availability by Vmax could be attributed to greater sodium channel mobilization during the slowed action potential upstrokes. The overestimation ...
The ordered electrical stimulation of the ventricles is achieved by a specialized network of fibres known as the Purkinje system. The gross anatomy and basic functional role of the Purkinje system is well understood. However, very little is known about the detailed anatomy of the Purkinje system, its inter-individual variability and the implications of the variability in ventricular function, in part due to limitations in experimental techniques. In this study, we aim to provide new insight into the inter-individual variability of the free running Purkinje system anatomy and its impact on ventricular electrophysiological function. As a first step towards achieving this aim, high resolution magnetic resonance imaging (MRI) datasets of rat and the rabbit ventricles are obtained and analysed using a novel semi-automatic image processing algorithm for segmentation of the free-running Purkinje system. Segmented geometry from the MRI datasets is used to construct a computational model of the Purkinje system,
Definition of Purkinje system in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is Purkinje system? Meaning of Purkinje system as a legal term. What does Purkinje system mean in law?
Rate-dependent changes in the electrical activity of sheep Purkinje fibres maintained at 37 °C have been investigated. The duration of the action potential is maximal at a frequency of about 60 min-1. When the rate is increased above 60 min-1 there is a substantial shortening of the action potential; this occurs abruptly in the first beat at the higher rate although subsequently there can be further changes in duration and these can result in a small prolongation, no change, or a small further shortening of the action potential and can take up to 10 min to reach a steady-state. When the rate is reduced from 60 min-1 there is also a shortening of the action potential but it occurs gradually over several hundred seconds. Action potential duration reaches a minimum value at a rate of about 6 min-1. 70% of preparations studied showed an increase in duration again at rates below 6 min-1 but duration is always constant at frequencies below about 0.1 min-1. The maximum diastolic potential is more ...
To test whether ryanodine blocks the release of calcium from the sarcoplasmic reticulum in cardiac muscle, we examined its effects on the aftercontractions and transient depolarizations or transient inward currents developed by guinea pig papillary muscles and voltage-clamped calf cardiac Purkinje fibers in potassium-free solutions. Ryanodine (0.1-1.0 microM) abolished or prevented aftercontractions and transient depolarizations by the papillary muscles without affecting any of the other sequelae of potassium removal. In the presence of 4.7 mM potassium and at a stimulation rate of 1 Hz, ryanodine had only a small variable effect on papillary muscle force development and action potential characteristics. In calf Purkinje fibers, ryanodine (1 nM-1 microM) completely blocked the aftercontractions and transient inward currents without altering the steady state current-voltage relationship. Ryanodine also abolished the twitch in potassium-free solutions, but it enhanced the tonic force during ...
Epinephrine promotes spontaneous activity in cardiac Purkinje fibers through its action on the pacemaker potassium current (iKK2). The mechanism of the acceleratory effect was studied by means of a voltage clamp technique. The results showed that the hormone speeds the deactivation of iKK2 during pacemaker activity by displacing the kinetic parameters of iKK2 toward less negative potentials. This depolarizing voltage shift is the sole explanation of the acceleratory effect since epinephrine did not alter the rectifier properties of iKK2, or the underlying inward leakage current, or the threshold for iNNa. The dose dependence of the voltage shift in the iKK2 activation curve was similar in 1.8 and 5.4 mM [Ca]o. The maximal voltage shift (usually ∼20 mV) was produced by epinephrine concentrations of , 10-6 M. The half-maximal effect was evoked by 60 nM epinephrine, nearly an order of magnitude lower than required for half-maximal effect on the secondary inward current (Carmeliet and Vereecke, ...
The effects of halothane (0.45 and 0.9 mM, equivalent to 0.7 and 1.5 vol%, respectively) and isoflurane (0.56 and 1.23 mM, equivalent to 0.9 and 2.0 vol%) on slowly inactivating Na+ current were examined by whole-cell voltage-clamp techniques. This approach allows evaluation of the role of anestheti …
In 1962, Denis Noble published one of the first mathematical models of a cardiac cell. By adapting the equations of the original Hodgkin-Huxley squid axon model (1952), Noble described the long lasting action and pace-maker potentials of the Purkinje fibres of the heart. The potassium-current equations differ from those of Hodgkin and Huxley in that the potassium ions are assumed to flow through two types of channel in the membrane. By contrast, the sodium current equations are very similar to those of Hodgkin and Huxley. The main failure of the Noble (1962) model is that it only includes one voltage gated inward current, INa. Calcium currents had not yet been discovered, but there was a clue in the model that something was missing. The only way the model could be made to work was to greatly extend the voltage range of the sodium current by reducing the voltage dependence of the sodium activation process. In effect the sodium current was made to serve the function of both the sodium and the ...
The pacemaker potential in Purkinje fibers is generated by a slow fall in potassium current which allows the inward background currents to depolarize the membrane. Adrenaline shifts the relation between activation of the potassium current and membrane potential in a depolarizing direction. Consequently, during the pacemaker potential, the potassium current falls more rapidly to lower values and the inward currents then depolarize the membrane more quickly. The shift in the potassium activation curve produced by adrenaline is large compared to that produced by calcium ions. The molecular action of adrenaline may involve either a large change in the surface charge of the membrane or a change in the dependence of the potassium permeability on the local electric field. ...
Cardiac muscle, like skeletal muscle and nerves, is electrically excitable. Local stimulation by a brief electrical shock of adequate strength generates an impulse that propagates in a regenerative...
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The effects of caffeine on rate-force relation and their Ca++ dependence were studied in canine cardiac Purkinje fibers. At constant rate, caffeine increased and then decreased force. During drives at different rates (15, 60 and 120/min), 1 mM caffeine caused the largest positive inotropic effect at the slowest rate, but in 8.1 mM [Ca++]o caffeine no longer increased force even at 15/min. Interruptions of drive were followed by a positive and then a negative staircase: caffeine (1-4 mM) blunted these effects. A sudden decrease in rate caused a positive staircase: caffeine decreased and caffeine plus 8.1 mM [Ca++]o abolished it. A sudden increase in rate caused a negative staircase and on recovery a positive staircase: caffeine reduced and caffeine plus 8.1 mM [Ca++]o could reverse them. In low [Ca++]o (0.54 mM), caffeine caused only a positive inotropic effect and did not modify the rate-force relation patterns. High [Ca++]o ( , 8.1 mM) reversed the staircase patterns induced by a rate increase; ...
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Outward Currents of the Sino-atrial Node . . . . . . . Regional Heterogeneity and Coupling to Atrial Tissue . . . . Bundle of His, Right and Left Bundle Branches and Purkinje Fibers Specialized Conducting Tissue Serves Two Roles . . . . . Membrane Currents in Purkinje Fibers and Myocytes that Flow During the Action Potential . . . . . . . . 3 Pacemaker Activity in Purkinje Fibers . . . . . . . . 3 Targets for Selective Intervention . . . . . . . . . . Rosen Giraud G, Latour H, Puech P (1960) Lactivité du noeud de Tawara et du faisceau de His en electrocardiographie chez lhomme. Arch Mal Coeur Vaiss 33:757-776 Goldberger E (1942) A single indifferent, electrocardiographic electrode of zero potential and a technique of obtaining augmented, unipolar, extremity leads. Am Heart J 23:483-492 Gray RA, Jalife J, Panfilov A, et al (1995) Nonstationary vortex like reentrant activity as a mechanism of polymorphic ventricular tachycardia in the isolated rabbit heart. Circ Res 28:403-414 Janse MJ, van ...
PR segment: This is a time of electrical quiescence during which the wave of electrical excitation (depolarization) passes through mainly the AV node. In addition the wave of depolarization moves through the bundle of HIS, bundle branches and purkinje fibers. Since the wave of depolarization moves through the AV node at a speed of about 1/100th the speed the wave moves through the bundle of HIS, bundle branches and purkinje fibers, most of the PR segment is associated with the passage of the wave of depolarization through the AV node ...
Histology image courtesy of Nathanael Reveal. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License ...
Histology image courtesy of Nathanael Reveal. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License ...
Atrioventricular resynchronisation alone has not been predictably effective in improving haemodynamics except in some patients with prolonged PR interval.2 Candidates for the implantation of a cardiac stimulator often present with intraventricular conduction disorders expressed as a widened QRS, an anomaly which may also be caused by the pacemaker itself. In the hope of minimising atrioventricular asynchrony, a delay is unfortunately imposed between right and left ventricular activation by stimulating the ventricle from the peripheral Purkinje network instead of preserving the normal sequence via the His bundle. This activation/contraction delay causes a delay in subsequent chamber relaxation, disturbing its filling (fig 3). As a result, the right-to-left electromechanical delay caused by typical pacing from the right ventricular apex may disrupt the synchrony of right and left ventricular systole. This spontaneous or iatrogenic asynchrony can be easily quantified by measuring the delay between ...
Sinus rhythm is the name given to the normal rhythm of the heart where electrical stimuli are initiated in the SA node, and are then conducted through the AV node and bundle of His, bundle branches and Purkinje fibres.. Depolarisation and repolarisation of the atria and ventricles show up as 3 distinct waves on ECG. A unique labelling system is used to identify each wave.. Although the diagram shows 5 waves, we will concentrate on 3 waves. You will not always see a Q wave or an S wave on an ECG.. This is why only 3 waves are emphasised when you are learning from scratch.. ...
Heart muscle cells generate electrical signals that are conducted through the heart by special fibers which stimulate the muscle of the heart to contract. The flow of electrical signals that starts the normal heartbeat begins in the sinus node and causes the atria, or upper chambers of the heart, to contract. The signal then travels through the atrioventricular, or AV node, bundle of His, bundle branches, and Purkinje fibers to stimulate the ventricles, or lower chambers of the heart, to contract and pump the blood out of the heart.. Request Stock Pricing. Parent Topic: Electrical System of the Heart ...
Okay Ill do the 4. questions first because Im relatively sure I can answer them correctly. The SA node sends a signal via the atrial-ventricular node (AV) down the purkinje fibres in the centre of the heart, causing it to contract from the bottom upwards (so the ventricles can empty themselves before the atria contract to fill them up again). The SA nodes also known as the pacemaker since it sets the rate at which the whole system moves. (Incidentally its one of the few parts of the nervous system that works completely independently of the brain ...
Okay Ill do the 4. questions first because Im relatively sure I can answer them correctly. The SA node sends a signal via the atrial-ventricular node (AV) down the purkinje fibres in the centre of the heart, causing it to contract from the bottom upwards (so the ventricles can empty themselves before the atria contract to fill them up again). The SA nodes also known as the pacemaker since it sets the rate at which the whole system moves. (Incidentally its one of the few parts of the nervous system that works completely independently of the brain ...
Cardiomyocytes from individual pluripotent control cells (hPSCs-CMs) could revolutionise biomedicine. into high articles commercial systems that assess framework, mitochondrial function, electrophysiology, calcium contractility and transients. This content can be component of a Particular Concern permitted: Cardiomyocyte Biology: Incorporation of Developmental and Environmental Cues in the Center modified by Marcus Schaub and Hughes Abriel. systems, such as ventricular sand iron arrangements [15] and Purkinje fibers [16], possess been utilized in physical and medicinal research thoroughly, but low-throughput and inter-species distinctions are restrictions. Types distinctions are highlighted in the mouse [13] particularly. While this types benefits from hereditary tractability via gene concentrating on, the defeat price of the mouse center can be ~?10 times faster than individual (500?bpm vs 60?bpm) and offers an electrocardiogram length 5C10 moments shorter (450?master of science vs ...
Anatomy medical lecture explaining the anatomy and musculature of heart, SA and AV node, Purkinje fibers, bundle of Hiss, heart cycle, branches of aorta and hypertension.
Vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized as a peptide prohormone in
Looking for online definition of Purkinje fibres in the Medical Dictionary? Purkinje fibres explanation free. What is Purkinje fibres? Meaning of Purkinje fibres medical term. What does Purkinje fibres mean?
TY - JOUR. T1 - Electrophysiological effects of alprenolol on depressed canine myocardium. AU - Guse, Paul A.. AU - Gaide, Marion S.. AU - Myerburg, Robert J.. AU - Epstein, Kristina. AU - Gelband, Henry. AU - Bassett, Arthur L.. PY - 1980/11. Y1 - 1980/11. N2 - The electrophysiological effects of the β-adrenergic antagonist, alprenolol, were compared in normal and depressed canine myocardium. Both (+) and (±)-alprenolol (5 x 10 -6 and 10 -5 mol.litre -1) decreased action potential amplitude and V̇max in Purkinje fibres superfused with Tyrodes solution in tissue bath. These concentrations shortened action potential duration and effective refractory period of Purkinje fibres but prolonged those of ventricular muscle. Alprenolol more markedly decreased V(max) and sometimes prevented action potential propagation in Purkinje fibres overlying infarcted regions. Similar depressant actions were noted in Purkinje fibres depolarised by exposure to 9 mmol.litre -1 K +. Depolarised and diseased ...
TY - JOUR. T1 - Effects of chemical subendocardial ablation on activation rate gradient during ventricular fibrillation. AU - Cha, Yong-Mei. AU - Uchida, T.. AU - Wolf, P. L.. AU - Peters, B. B.. AU - Fishbein, M. C.. AU - Karagueuzian, H. S.. AU - Chen, P. S.. PY - 1995. Y1 - 1995. N2 - The mechanism by which an endocardial-epicardial activation rate gradient develops after 1 or 2 min of sustained ventricular fibrillation is unknown. We recorded from electrodes on the epicardium and from hook electrodes in the endocardium in three open-chest control dogs during prolonged ventricular fibrillation. The same recordings were also made in seven dogs after right ventricular subendocardial ablation with Lugol solution and in three dogs after substitution of air for the cavitary blood. The effects of these interventions, i.e., Lugol ablation (n = 2) and the exposure to air (n = 2), on the subendocardial Purkinje fiber transmembrane action potential properties were also evaluated in vitro using ...
Cardiac conduction system - Animation A network of specialized muscle cells is found in the hearts walls. These muscle cells send signals to the rest of the heart muscle causing a contraction. This group of muscle cells is called the cardiac conduction system. The main parts of the system are the SA node, AV node, bundle of HIS, bundle branches, and Purkinje fibers. Lets follow a signal through the contraction process. The SA node starts the sequence by causing the atrial muscles to contract. Thats why doctors sometimes call it the anatomical pacemaker. Next, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an electrocardiogram, or EKG. Doctors use an EKG to see how well the cardiac conduction system works. Any changes on the EKG can mean serious problems. ...
Patients with chronic constipation benefit from treatment with 5-hydroxytryptamine 4 (5-HT4) receptor agonists. However, the first-generation 5-HT4 receptor agonists cisapride and tegaserod were withdrawn from the market owing to rare cardiovascular adverse events, which were not 5-HT4-receptor-related, but due to the lack of selectivity of these drugs. Here we report the nonclinical cardiovascular profile of the selective 5-HT4 receptor agonist prucalopride. To assess its non-5-HT4 receptor-mediated effects on cardiovascular electrophysiological parameters, in vitro studies were performed in human ether-a-go-go-related gene-transfected cells, guinea pig ventricular myocytes and papillary muscle preparations, rabbit and dog Purkinje fibers, and the Langendorff rabbit heart. In vivo experiments were performed in a rabbit model for drug-induced proarrhythmogenesis, in anesthetized guinea pigs, and anesthetized and conscious dogs. In addition, human platelet aggregation and coronary artery ...
Procainamide (PA) increases the effective refractory period of the atria, and to a lesser extent the bundle of His-Purkinje system and ventricles of the heart. It reduces impulse conduction velocity in the atria, His-Purkinje fibers, and ventricular muscle, but has variable effects on the atrioventricular (A-V) node, a direct slowing action and a weaker vagolytic effect which may speed A-V conduction slightly. Myocardial excitability is reduced in the atria, Purkinje fibers, papillary muscles, and ventricles by an increase in the threshold for excitation, combined with inhibition of ectopic pacemaker activity by retardation of the slow phase of diastolic depolarization, thus decreasing automaticity especially in ectopic sites. Contractility of the undamaged heart is usually not affected by therapeutic concentrations, although slight reduction of cardiac output may occur, and may be significant in the presence of myocardial damage. Therapeutic levels of PA may exert vagolytic effects and produce ...
Continuing with the previous analogy, lets say that you have a sand castle on the beach (this will be your AV node). Every time one of the ripples hits the sand castle (AV node), it can cause depolarization that will run through the His Purkinje system. Normally, this is in a 1:1 ratio.. HOWEVER, in atrial fibrillation, there are MANY ripples (i.e. waves of depolarization) hitting the sand castle (AV node), constantly, and so the AV node is constantly being depolarized. Each time the AV node is depolarized enough to launch an action potential, the His Purkinje system (and thus the ventricle) will fire ...
A method and apparatus for efficiently charging lead-acid batteries applies small voltage steps to probe the charging efficiency of a battery being charged. The application of a voltage step causes the current to change from a base current to a surge current immediately after the voltage step, and to decay asymptotically to a plateau current after the surge current. A current ratio, defined as the difference between the plateau current and the base current divided by the difference between the surge current and the base current, is used as an indicator of the charging efficiency. The output voltage of the power supply charging the battery is then adjusted according to the measured current ratio. A current-voltage slope, defined as the difference between the plateau current and the base current divided by the magnitude of the voltage step, may also be used as an indicator of the charging efficiency for controlling the charging process. Alternatively, in a current-controlled charging process, small
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A resource for neurologists, neurology residents, medical students on a neurology rotation, and people interested in neurology or neuroscience. Review questions to help you study for the Neurology boards or RITE exam. Helpful PDA medical software.
Definition of Purkinje cell in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is Purkinje cell? Meaning of Purkinje cell as a legal term. What does Purkinje cell mean in law?
The Purkinje network has the potential to influence myocardial AP morphology and rate-dependent behaviour, and furthermore to underlie enhanced transmural APD heterogeneities and spatial gradients of APD in non-failing and failing myocardium.
The Conduction System of the Mammlian Heart: An Anatomico-Histological Study of the Atrioventricular Bundle and the Purkinje Fibers (Cardiopulmonary Medicine from I*C*P*, Volume 234) http://s10.postimg.org/ws4yk7trt/The_Conduction_System_of_the_Mammlian_Heart.jpg By Sunao Tawara, Kozo Suma, Munehiro Shimada Hardcover: 256 pages Publisher: WSP Co; 1 edition (September 1, 1998) Language: English ISBN-10: 1860941168 ISBN-13: 978-1860941160
Principal Investigator:IMANISHI Sunao, Project Period (FY):1997 - 1998, Research Category:Grant-in-Aid for Scientific Research (C), Section:一般, Research Field:Circulatory organs internal medicine
TY - JOUR. T1 - Automaticity and entrance block induced by focal depolarization of mammalian ventricular tissues. AU - Ferrier, G. R.. AU - Rosenthal, J. E.. PY - 1980/1/1. Y1 - 1980/1/1. N2 - Isolated canine interventricular septa were studied with standard microelectrode techniques. Focal automaticity was induced by applying depolarizing current through an extracellular pipet in contact with the right bundle branch (RBB) of the ventricular specialized conducting system. Automaticity appeared with depolarization to transmembrane potentials of -50 mV or less. The spontaneous activity was neither depressed nor accelerated when overdrive suppression was attempted. Activity originating within the focus propagated into fully polarized surrounding tissue. However, entrance block, phasically related to the spontaneous cycle length, was an intrinsic property of these foci. Early premature beats initiated outside the focus failed to enter the focus, but the resulting electrotonus delayed the next ...
Purkinje nerve cells. Coloured scanning electron micrograph (SEM) of two Purkinje nerve cells from the cerebellum of the brain, the part of the brain that controls balance, posture and muscle co- ordination. The cerebellum is composed of outer layers of grey matter and an inner core of white matter. Within the grey matter are Purkinje nerve cells (two large bodies), from which branch many thread-like dendrites. These dendrites relay nerve impulses to the Purkinje cells. Magnification: x1250 when printed 10 centimetres wide. - Stock Image P360/0325
Electro cardio gram. It is a common noninvasive diagnostic test that evaluate the heart function. By recording electrical activity. P wave-- : fist +ve deflation. it represent atrial depolarization (contraction). Time is 0-12sec. PR interval:- it is represent the time it taken an impulse from the AV node to the bundle of Hiss, and to bundle branch to the purkinje fiber,. Normal PR interval duration ranges from 0.12 to 0.20sec. QRS complex: - represent ventricle depolarization normal duration ranges from 0.08 to 0.12sec. ST segment: - begin at the end of an S- wave and up to the beginning of T-wave. It represent the part of ventricle repolarization. Normal time of ST segment is less than 0.20sec. T-wave: - indicate ventricular repolarization. Time taken for this is less than 0.20sec. U-wave: - may follow T-wave, prominent U wave may indicate hypokalemia. Measuring heart rate from ECG. ...
abnormalities acid acute angiogenesis angiotensin antibodies apoptosis arrhythmias associated atherosclerosis binding Biol Chem blood cardiac cardiomyopathy cellular cholesterol chronic Circ Res Circulation Clin Invest clinical cloning coronary artery cytokines diabetes dilated effects embryonic endothelial cells endothelium enzyme expression fibrinolysis formation function gene transfer genetic genome GP IIb/IIIa growth factor heart failure human hypertrophic cardiomyopathy hypertrophy increased induced inhibition inhibitor insulin integrin ischemia ischemic JAm Coll Cardiol kinase left ventricular lesions levels lipid lipoprotein macrophages mechanisms metabolism mice molecular molecules monocytes mouse mutations myocardial infarction myocardium myocytes Natl Acad Sci neointimal nitric oxide pathway patients phenotype plasma plasmin plasminogen plasminogen activator platelet polymorphism Proc Natl Acad proliferation protein pulmonary hypertension Purkinje fibers receptor reduced remodeling ...
Enhanced cardiac automaticity refers to the accelerated generation of an action potential by either normal pacemaker tissue (enhanced normal automaticity) or by abnormal tissue within the myocardium (abnormal automaticity). The discharge rate of norm
In a prospective study of 1012 patients above the age of 12 years, we detected 4 (0.4%) cases of left ventricular false tendon (LVFT) by echocardiography. Two patients had significant heart disease and LVFT was perhaps a chance occurrence; two others
PoPuPS is een realisatie van les Bibliothèques van de Université de Liège.. Aangedreven door Lodel , Toegang administrator. ...
Reflections of outside objects in the eye. Do you remember how annoying anime characters always have one or more white blotches in their eyes? Those ar...
From routine checkups to treatments for surgery, The Ankle & Foot Clinic of Erie is equipped to handle all your foot and ankle care needs.
"Purkinje Fibers". About.com. 9 April 2012. Archived from the original on 14 April 2012. Retrieved 7 June 2012. Guyton & Hall ... In the ventricles the signal is carried by specialized tissue called the Purkinje fibers which then transmit the electric ... The ventricles are more richly innervated by sympathetic fibers than parasympathetic fibers. Sympathetic stimulation causes the ... Although Purkinje fibers and the bundle of His were discovered as early as the 19th century, their specific role in the ...
The Purkinje fibers are additional myocardial conductive fibers that spread the impulse to the myocardial contractile cells in ... The Purkinje fibers have a fast inherent conduction rate, and the electrical impulse reaches all of the ventricular muscle ... Both bundle branches descend and reach the apex of the heart where they connect with the Purkinje fibers. This passage takes ... The bundle branches would have an inherent rate of 20-30 impulses per minute, and the Purkinje fibers would fire at 15-20 ...
Finally, the electrical signal travels into the Purkinje fibers. The division of the signal into a right and left bundle and ... then into the Purkinje fibers allows for a simultaneous depolarization and contraction of the right and left ventricles. The ... Mobitz II is caused by a sudden, unexpected failure of the His-Purkinje cells to conduct the electrical impulse. On ECG, the PR ...
Excitation of cerebellar Purkinje cells by the climbing fibers. Nature 203: 245-246, 1964 Illustration and text: cere/text/p3/ ... They terminate directly on Purkinje cells as the climbing fiber input system. This article incorporates text in the public ... The olivocerebellar tract, also known as olivocerebellar fibers, are neural fibers which originate at the olivary nucleus and ... then as internal arcuate fibers they pass partly through and partly around the opposite olive and enter the inferior peduncle ...
Tsien, R. W.; Carpenter, D. O. (1978-06-01). "Ionic mechanisms of pacemaker activity in cardiac Purkinje fibers". Federation ... and then to the purkinje fibers at the bottom (apex) of the heart, causing ventricular contraction. This is known as the ... This means that before the AVN or purkinje fibres reach the threshold potential for an action potential, they are depolarized ... purkinje fibres = 20-40 beats per minute). These pacemakers will keep a patient alive until the emergency team arrives. An ...
Tsien, R. W.; Carpenter, D. O. (1 June 1978). "Ionic mechanisms of pacemaker activity in cardiac Purkinje fibers". Federation ... Other cells within the heart (including the Purkinje fibers and atrioventricular node) can also initiate action potentials; ...
"Postsynaptic Glutamate Transport at the Climbing Fiber-Purkinje Cell Synapse". "Interactions between glutamate transporters and ... ATXN2 antisense therapy improves SCA2 mouse motor and Purkinje cell electrophysiological phenotypes, Nature, 544, 362-366. ...
U' waves are thought to represent repolarization of the Purkinje fibers.[1][2] However, the exact source of the U wave remains ... It is possible to take this momentum back to Purkinje fibers along the vessels of the myocardium. This idea is also proved by ... coronary and insufficiency have momentum there is no possibility to move to the Purkinje fibers, therefore, the ECG recorded a ...
"4-Aminopyridine and the early outward current of sheep cardiac Purkinje fibers". J Gen Physiol 1979;73:139-157. Zygmunt AC, ... Sipido KR, Callewaert G, Carmeliet E. "[Ca2+]i transients and [Ca2+]i-dependent chloride current in single Purkinje cells from ... Current Contributes to Delayed After depolarizations in Single Purkinje and Ventricular Myocytes". Circulation 2000;101:2639- ...
Mechanism of action on the pacemaker potential in cardiac Purkinje fibers". Science. 162 (3856): 916-7. Bibcode:1968Sci...162.. ... Noble, D; Tsien, R. W. (1968). "The kinetics and rectifier properties of the slow potassium current in cardiac Purkinje fibres ... McAllister, R. E.; Noble, D; Tsien, R. W. (1975). "Reconstruction of the electrical activity of cardiac Purkinje fibres". The ... Noble, D; Tsien, R. W. (1969). "Outward membrane currents activated in the plateau range of potentials in cardiac Purkinje ...
These bundles and fascicles give rise to thin filaments known as Purkinje fibers. These fibers distribute the impulse to the ... The fascicular branches then lead to the Purkinje fibers, which provide electrical conduction to the ventricles, causing the ... Atrioventricular node Bachmann's bundle Bundle branches Bundle of Kent Purkinje Fibers Sinoatrial node Logan, Carolynn M.; Rice ... These specialized muscle fibers in the heart were named after the Swiss cardiologist Wilhelm His Jr., who discovered them in ...
These structures lead to a network of thin filaments known as Purkinje fibers. They play an integral role in the electrical ... conduction system of the heart by transmitting cardiac action potentials from the bundle of His to the Purkinje fibers. There ... conduction system of the heart by transmitting cardiac action potentials to the Purkinje fibers. When a bundle branch or ...
Iacono G, Vassalle M (April 1990). "On the mechanism of the different sensitivity of Purkinje and myocardial fibers to ... "Effect of calcium on acetylstrophanthidin-induced transient depolarizations in canine Purkinje tissue". Circulation Research. ...
... projects climbing fibers to innervate Purkinje cells. The other four nuclei (the external cuneate nucleus, the lateral ... Mossy fibers, which are mostly found in the precerebellar nuclei, make contact with granule cells in the IGL. Granule neurons ... The expansion of the EGL precursor cells creates a large population of neurons that outnumber Purkinje cells 250:1 in the adult ... Meanwhile, cells in the ventricular zone evolve into GABAergic Purkinje cells (another type of cerebellar neuron) and deep ...
These electrical pathways contain the sinoatrial node, the atrioventricular node, and the Purkinje fibers. (Exceptions such as ... The cardiac action potential spreads distally (or outwardly) to the small branches of the Purkinje tree via the flux of cations ... The cardiac action potential is propagated down electrical pathways through the bundle of His to the Purkinje fibres; this ...
Snyders DJ, Van Bogaert P-P: Alinidine modifies the pacemaker current in sheep Purkinje fibers. Pflügers Arch 1987, 410:83-91 ...
Depolarization of the heart ventricles occurs almost simultaneously, via the bundle of His and Purkinje fibers. If they are ...
These Purkinje fibers (p-fibers) found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the ... Parto, P.; Tadjalli, M.; Ghazi, S. R. & Salamat, M. A. (2013). "Distribution and Structure of Purkinje Fibers in the Heart of ... Moderator bands, full of Purkinje fibers, are found in different locations in the left and right ventricles. These bands are ... The sinoatrial node shows a small concentration of Purkinje fibers, however, continuing through the conducting pathway of the ...
Vestibular inputs are also carried through climbing fibers that project into the flocculus, stimulating Purkinje cells. Leading ... The climbing fibers then send the image or projection to the part of the brain that receives electrical signals and generates ... The "halves" of the flocculus refer to the caudal half and the rostral half, and they indicate from where fiber projections are ... These "zones" of the flocculus refer to five separate groupings of Purkinje cells that project to different areas of the brain ...
Note that these Purkinje fibers are muscle fibers and not related to the Purkinje cells, which are neurons found in the ... Action potentials from the AV node travel through the bundle of His and thence to the Purkinje fibers. Conversely, anomalies in ... 3: 253-8. Ling G, Gerard RW (December 1949). "The normal membrane potential of frog sartorius fibers". Journal of Cellular and ... Hartline DK, Colman DR (January 2007). "Rapid conduction and the evolution of giant axons and myelinated fibers". Current ...
Purkinje fibers are occasionally capable of acting as the default or "escape" pacemaker. The reason Purkinje cells do not ... The left and right branches of this bundle, and the Purkinje fibers, will also produce a spontaneous action potential at a rate ... This native rate is constantly modified by the activity of sympathetic and parasympathetic nerve fibers via the autonomic ...
He credited Tawara for connecting the bundle with the Purkinje fibers and for declaring it the heart's conduction system. ... and descends into the terminal ends of the Purkinje fibers. Tawara commented that the system represents a transporting or ... and the anatomy of the whole system and the connections with the network of Purkinje were described in great detail and in many ... Purkinje cells act as a pathway for the "atrioventricular connecting system". The atrioventricular connecting system starts in ...
Purkinje fibers). This property helps eliminate repolarization dispersion, a proarrhythmial effect noted in class III agents. ... Electrophysiological characterization of BRL-32872 in canine purkinje fiber and ventricular muscle: Effect on early after- ...
The two bundle branches taper out to produce numerous Purkinje fibers, which stimulate individual groups of myocardial cells to ... the electrical signal diverges and is conducted through the left and right bundle of His to the respective Purkinje fibers for ... "Cardiac Muscle Fibers". ZY 560 Mammalian Physiology. Auburn University. Archived from the original on June 1, 2005. Retrieved ...
Kline RP, Cohen I, Falk R, Kupersmith J: Activity dependent extracellular K+ fluctuation in canine Purkinje fiber. Nature 286: ... Kline, RP; Cohen, I; Falk, R; Kupersmith, J (1980). "Activity-dependent extracellular K+ fluctuations in canine Purkinje fibres ...
This brain region contains three main neuronal cell types- Purkinje cells, granule cells and mossy fiber cells. Wnt-3 ... In this path, a "fast" motoneuron can convert any muscle fiber into a fast-twitch muscle fiber. There is evidence for both ... fast-twitch muscle fibers are innervated by "fast" motoneurons, and slow-twitch muscle fibers are innervated by "slow" ... Muscle fibers are innervated by a single input and operate in an all or none fashion. Coupled with the plasticity that is ...
Patients with ataxia and CD have antibodies that react with Purkinje fibers but is restricted to the anti-gliadin IgA/IgG. A ...
Reentry occurs when an area of 1-way block in the Purkinje fibers and a second area of slow conduction are present. This ... A premature ventricular contraction (PVC) is a relatively common event where the heartbeat is initiated by Purkinje fibers in ... However, when a PVC occurs the impulse nearly always travels through only one bundle fiber, so there is no neutralization ... During ventricular activation, one bundle tract's area of slow conduction activates the other tract's bundle fibers post block ...
... and the application of this principle to mathematical models of the Purkinje fibers in the heart. In 2012, she became one of ...
In optical fibers[edit]. Rayleigh scattering is an important component of the scattering of optical signals in optical fibers. ... Purkinje effect).[citation needed] ... Silica fibers are glasses, disordered materials with ...
Purkinje fibers. Pericardial cavity. *pericardial sinus. Pericardium. *fibrous pericardium *sternopericardial ligaments. * ...
For example, JCV has been found to infect the granule cell layer of the cerebellum, while sparing purkinje fibers, ultimately ...
In vertebrates, 1 represents the retina and 2 is the nerve fibers, including the optic nerve (3), whereas in the octopus eye, 1 ... Purkinje images ...
The commissural fibers or transverse fibers are axons that connect the two hemispheres of the brain. In contrast to commissural ... fibers, association fibers connect regions within the same hemisphere of the brain, and projection fibers connect each region ... the olfactory fibers and 2) the non-olfactory fibers.[5] ... Wikimedia Commons has media related to Commissural fibers.. *v ... The commissural fibers make up tracts that include the corpus callosum, the anterior commissure, and the posterior commissure. ...
These purkinje fibers (p-fibers) found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the ... Moderator bands, full of purkinje fibers, are found in different locations in the left and right ventricles.[68] These bands ... Parto, P.; Tadjalli, M.; Ghazi, S. R. & Salamat, M. A. (2013). "Distribution and Structure of Purkinje Fibers in the Heart of ... continuing through the conducting pathway of the heart the bundle of his shows the highest amount of these purkinje fibers.[71] ...
Purkinje fibers. Pericardial cavity. *pericardial sinus. Pericardium. *fibrous pericardium *sternopericardial ligaments. * ...
These parallel fibers form thousands of excitatory Granule-cell-Purkinje-cell synapses onto the dendrites of Purkinje cells. ... The parallel fibers are sent up through the Purkinje layer into the molecular layer where they branch out and spread through ... Plasticity of the synapse between a parallel fiber and a Purkinje cell is believed to be important for motor learning.[11] The ... These parallel fibers form thousands of excitatory granule-cell-Purkinje-cell synapses onto the intermediate and distal ...
fibers *Ia or Aα. *Ib or Golgi or Aα. *II or Aβ and Aγ ...
Normally the heartbeat is initiated in the SA node of the atrium but initiation can also occur in the Purkinje fibres of the ...
fibers *Ia or Aα. *Ib or Golgi or Aα. *II or Aβ and Aγ ...
The effect upon Purkinje fibers and ventricles is negligible. Automaticity is also increased in the atria, AV node, Purkinje ... fibers, and ventricles. ECG changes seen in a patient taking digoxin include increased PR interval (due to decreased AV ...
Whilst in a minority of cases some form of intranodal or paranodal fibers that bypass all or part of the atrioventricular node ... because ventricular conduction is via the His-Purkinje system. Lown-Ganong-Levine syndrome is a clinical diagnosis that came ... can be found with subsequent conduction down the normal His-Purkinje system, in most cases the short PR interval is caused by ...
Note that these Purkinje fibers are muscle fibers and not related to the Purkinje cells, which are neurons found in the ... Action potentials from the AV node travel through the bundle of His and thence to the Purkinje fibers.[note 2] Conversely, ... Image of two Purkinje cells (labeled as A) drawn by Santiago Ramón y Cajal in 1899. Large trees of dendrites feed into the soma ... Nastuk WL (1950). "The electrical activity of single muscle fibers". J. Cell. Comp. Physiol. 35: 39-73. doi:10.1002/jcp. ...
Conduction system: Cardiac pacemaker · SA node · AV node · bundle of His · Purkinje fibers ...
Intracellular Calcium Dynamics Permit a Purkinje Neuron Model to Perform Toggle and Gain Computations Upon its Inputs.. ... 聯絡纖維(英語:Template:Association fibers). *連合纖維(英語:Template:Commissural fibers and septum) ...
His observations on fiber nodes and the degeneration and regeneration of cut fibers had a great influence on Parisian neurology ... Myelination of nerve fibers[edit]. The complex changes that the Schwann cell undergoes during the process of myelination of ... The size and the spacing of the internodes vary with the fiber diameter in a curvilinear relationship that is optimized for ... Soon afterwards, he discovered gaps in sheaths of nerve fibers, which were later called the Nodes of Ranvier. This discovery ...
sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal ... Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei ... 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal ... 1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex) ...
No photoreceptors are found at the blind spot, the area where ganglion cell fibers are collected into the optic nerve and leave ...
Purkinje fibers. Страница 537[редактиране , редактиране на кода]. *muscular structure of the heart *fibers of the atria * ...
cell body fiber. • integral component of plasma membrane. • dendritic shaft. • axon. • neuronal cell body. • caveola. • ... Maeshima T, Shiga T, Ito R, Okado N (December 2004). "Expression of serotonin2A receptors in Purkinje cells of the developing ... "Serotonin2A receptor-like immunoreactivity in rat cerebellar Purkinje cells". Neuroscience Letters. 252 (1): 72-4. doi:10.1016/ ...
Purkinje fibers. Pericardial cavity. *pericardial sinus. Pericardium. *fibrous pericardium *sternopericardial ligaments. * ...
Purkinje cells → deep nuclei. The other main pathway is from the climbing fibers and these project to Purkinje cells and also ... sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal ... In the cerebellum one of the two major pathways is that of the mossy fibers. Mossy fibers project directly to the deep nuclei, ... 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal ...
In the mature synapse each muscle fiber is innervated by one motor neuron. However, during development many of the fibers are ... "Traveling waves in developing cerebellar cortex mediated by asymmetrical Purkinje cell connectivity". Nature Neuroscience. 12 ... Miyata T, Kawaguchi A, Okano H, Ogawa M (September 2001). "Asymmetric inheritance of radial glial fibers by cortical neurons". ... whose fibers serve as a scaffolding for migrating cells and a means of radial communication mediated by calcium dynamic ...
At the end of the bundle branches, the electrical impulse goes into the ventricular muscle through the Purkinje Fibers. This is ... The order is: Sino-Atrial Node → Atria (systole) → Atrio-Ventricular Node → Bundle of His → Bundle branches → Purkinje Fibers ...
It was originally thought to be an independent globular corpuscle suspended along nerve fibers that looped and coiled.[3] It ... Golgi I neurons have long axons that can move signals over long distances, such as in Purkinje cells, whereas Golgi II neurons ...
... for the in vivo B-DNA X-ray diffraction-scattering patterns of highly hydrated DNA fibers in terms of squares of Bessel ... "The nuclear DNA base 5-hydroxymethylcytosine is present in Purkinje neurons and the brain". Science. 324 (5929): 929-30. ... analyses based on Patterson transforms that provided only a limited amount of structural information for oriented fibers of DNA ...
Anatomy Atlases - Microscopic Anatomy, plate 06.114 - "Spinal Root Nerve Fibers". *Diagram at tcc.fl.edu (look for #2) ...
sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal ... Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei ... 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal ... Thalamocortical fibers have a bush or tree-like appearance as they extend into the internal capsule and project to the layers ...
... the Purkinje fibers are distinctly shielded from each other by collagen or the cardiac skeleton. The Purkinje fibers are ... Purkinje fibers are a unique cardiac end-organ. Further histologic examination reveals that these fibers are split in ... The Purkinje fibers (/pɜːrˈkɪndʒi/ pur-KIN-jee; Purkinje tissue or subendocardial branches) are located in the inner ... The Purkinje fibers are specialized conducting fibers composed of electrically excitable cells. They are larger than ...
... any of the specialized cardiac muscle fibers forming a network in the ventricular walls that conduct electric impulses ... purkinje fiber. in Medicine. Purkinje fiber. n.. *Any of the specialized cardiac muscle fibers, part of the impulse-conducting ... Origin of Purkinje fiber. named after Jan Evangelista Purkinje (Czech Purkyně) (1787-1869), Czech physiologist, who discovered ... any of the specialized cardiac muscle fibers forming a network in the ventricular walls that conduct electric impulses ...
Tsien, R. W. Effects of epinephrine on the pacemaker current of cardiac Purkinje fibers. J. Gen Physiol. 64: 293-319, 1974. ... Kass R.S., Bennett P.B. (1985) Microelectrode Voltage Clamp: The Cardiac Purkinje Fiber. In: Smith T.G., Lecar H., Redman S.J ... Block of outward current in cardiac Purkinje fibers by injection of quaternary ammonium ions. J. Gen. Physiol. 79: 1041-1063, ... Three-microelectrode voltage clamp experiments in calf cardiac Purkinje fibers: is slow inward current adequately measured? J. ...
Purkinje fibers are specialized muscle fibers in the heart that relay impulses from the atrioventricular bundle to the ... Purkinje fibers were discovered in 1839. Purkyne, spelled alternatively at Purkinje, also discovered Purkinje cells, which are ... Purkinje fibers refer to specialized muscle fibers in the heart that are located beneath the innermost layer of the heart, ... Purkinje fibers are specialized muscle fibers found in the heart. They originate at the atrioventricular bundle and extend into ...
Antiarrhythmic effects of nicorandil on canine cardiac Purkinje fibers.. Imanishi S, Arita M, Aomine M, Kiyosue T. ... was investigated electrophysiologically with regard to the action potentials of canine Purkinje fibers. The main results ...
Purkinje fibers are special fibers that are located in the atrioventricular, or AV, bundle of the heart. Their function is to ... However, the Purkinje fibers do not actually set the heart rate.. The fibers were discovered by Jan Evangelista Purkyne, a ... Purkinje fibers are special fibers that are located in the atrioventricular, or AV, bundle of the heart. Their function is to ... The Purkinje fibers can be found in the ventricle walls, which are at the bottom of the heart in an area called the ...
... Nat Neurosci. 2002 Aug;5(8):725-6. doi: ... Here we report that LTD at the climbing fiber-Purkinje cell synapse in rat cerebellum was not associated with changes in a ...
2011) Developmental switching of perisomatic innervation from climbing fibers to basket cell fibers in cerebellar Purkinje ... 1975) Climbing fiber deafferentation: its action on Purkinje cell dendritic spines. Brain Res 98:574-581, doi:10.1016/0006-8993 ... 2011) Climbing fiber synapse elimination in cerebellar Purkinje cells. Eur J Neurosci 34:1697-1710, doi:10.1111/j.1460- ... 1988) Number of parallel fiber synapses on an individual Purkinje cell in the cerebellum of the rat. J Comp Neurol 274:168-177 ...
... Neuron. 2006 Oct 19 ... A recently discovered postsynaptic form of LTP at cerebellar parallel fiber (PF)-Purkinje cell (PC) synapses provides a ...
Purkinje fibers - histology slide This histology slide shows purkinje fibers in H&E stained cardiac muscle.. Histology image ...
Differential blocking action of Joro spider toxin analog on parallel fiber and climbing fiber synapses in cerebellar Purkinje ... Evidence that Climbing Fibers Control an Intrinsic Spike Generator in Cerebellar Purkinje Cells. Nadia L. Cerminara and John A ... the mossy fiber-parallel fiber (MF-PF) pathway and the climbing fiber (CF) pathway. These two pathways each generate a distinct ... It is well established that the climbing fiber (CF) input to a cerebellar Purkinje cell (PC) can exert a controlling influence ...
Demonstrating purkinje fibers, the modified cardiac muscle fibers which occur on the periphery of the cell. These fibers ... Heart, Purkinje Fibers. Iron Hematoxylin. Section. Each. Retrieving. The minimum order for this item is . ...
The pacemaker potential in Purkinje fibers is generated by a slow fall in potassium current which allows the inward background ... Adrenaline: Mechanism of Action on the Pacemaker Potential in Cardiac Purkinje Fibers ... Adrenaline: Mechanism of Action on the Pacemaker Potential in Cardiac Purkinje Fibers ... Adrenaline: Mechanism of Action on the Pacemaker Potential in Cardiac Purkinje Fibers ...
Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model. Paul B ... Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model ... Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model ... Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model ...
Duration of action potential in vitro against Canine Purkinje fibers; at 1 uM concentration. ...
Actions of verapamil on Purkinje fibers from normal and infarcted heart tissues.. G H Dersham and J Han ... Actions of verapamil on Purkinje fibers from normal and infarcted heart tissues.. G H Dersham and J Han ... Actions of verapamil on Purkinje fibers from normal and infarcted heart tissues.. G H Dersham and J Han ... Effects of 1 microM verapamil on action potentials of Purkinje fibers from normal and infarcted zones (NZ and IZ) were studied ...
An improved catheter is provided that is particularly useful for mapping the Purkinje fibers for potential diagnosis of ... US7089045B2 - Catheter and method for mapping Purkinje fibers - Google Patents. Catheter and method for mapping Purkinje fibers ... Catheter and method for mapping purkinjes fiber JP4503254B2 (en) * 2002-08-30. 2010-07-14. バイオセンス・ウエブスター・インコーポレーテツド. Catheter ... Catheter and method for mapping purkinjes fiber US20060106296A1 (en) * 2002-10-30. 2006-05-18. Mejia Ruth N. Multi-tip ...
Interaction experiments on the responses evoked by Purkinje cells by climbing fibers ... Activity of Purkinje cells, parallel fibers, and climbing fibers in the developing rabbit cerebellum. Developmental ... Glutamate and synaptic depolarization of Purkinje cells evoked by parallel fibers and by climbing fibers. Brain Research 170(2 ... Developmental switching of perisomatic innervation from climbing fibers to basket cell fibers in cerebellar Purkinje cells. ...
A WB 4101-sensitive alpha-1 adrenergic receptor subtype modulates repolarization in canine Purkinje fibers.. J H Lee, S F ... A WB 4101-sensitive alpha-1 adrenergic receptor subtype modulates repolarization in canine Purkinje fibers.. J H Lee, S F ... A WB 4101-sensitive alpha-1 adrenergic receptor subtype modulates repolarization in canine Purkinje fibers.. J H Lee, S F ... We used standard microelectrode techniques to study alpha-1 adrenergic modulation of repolarization in canine Purkinje fibers. ...
... код для вставки. код для вставки на сайт или в блог ... If the Purkinje fibers represent tissue specialized for the same type of contractility as heart muscle, one would expect them ... Figures 2A and 2B are high-power drawings of small areas of the Purkinje fibers (2,4) and heart muscle (2B) shown in figure 1. ... 2 Figures 2A and 2B are high-power drawings of small areas of the Purkinje fibers (2A) and heart muscle (2B) shown in figure 1 ...
CaMKII, calcium signals, cerebellum, fiber-Purkinje cell synapse, plasticity, synaptic depression Persistent URL. dx.doi.org/ ... βCaMKII controls the direction of plasticity at parallel fiber-Purkinje cell synapses. Publication. Publication. ... is important for controlling the direction of plasticity at the parallel fiber-Purkinje cell synapse; a protocol that induced ... βCaMKII controls the direction of plasticity at parallel fiber-Purkinje cell synapses. doi:10.1038/nn.2329 ...
Epinephrine promotes spontaneous activity in cardiac Purkinje fibers through its action on the pacemaker potassium current (iK ... Effects of Epinephrine on the Pacemaker Potassium Current of Cardiac Purkinje Fibers. Richard W. Tsien ... Effects of Epinephrine on the Pacemaker Potassium Current of Cardiac Purkinje Fibers ...
Glutamate and synaptic depolarization of Purkinje cells evoked by parallel fibers and by climbing fibers ... Activity of Purkinje cells, parallel fibers, and climbing fibers in the developing rabbit cerebellum. Developmental ... Long lasting depressions of parallel fiber purkinje cell transmission caused by conjunctive stimulation of parallel fibers and ... Long-lasting depression of parallel fiber-Purkinje cell transmission induced by conjunctive stimulation of parallel fibers and ...
At the cellular level, we show that Ca V3.1 channels are required for long-term potentiation at parallel fiber-Purkinje cell ... T-type channel blockade impairs long-term potentiation at the parallel fiber-Purkinje cell synapse and cerebellar learning. ... CaV3.1 T-type channels are abundant at the cerebellar synapse between parallel fibers and Purkinje cells where they contribute ... T-type channel blockade impairs long-term potentiation at the parallel fiber-Purkinje cell synapse and cerebellar learning. ...
Mechanisms of action of lidocaine and quinidine on action potential duration in rabbit cardiac Purkinje fibers. An effect on ... Mechanisms of action of lidocaine and quinidine on action potential duration in rabbit cardiac Purkinje fibers. An effect on ... Mechanisms of action of lidocaine and quinidine on action potential duration in rabbit cardiac Purkinje fibers. An effect on ... Mechanisms of action of lidocaine and quinidine on action potential duration in rabbit cardiac Purkinje fibers. An effect on ...
Furthermore, FAR-2 is also expressed by one type of Purkinje cell afferents, namely, the climbing fibers, and different ... Furthermore, FAR-2 is also expressed by one type of Purkinje cell afferents, namely, the climbing fibers, and different ... The contactin-related protein FAR-2 defines purkinje cell clusters and labels subpopulations of climbing fibers in the ... The contactin-related protein FAR-2 defines purkinje cell clusters and labels subpopulations of climbing fibers in the ...
Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. ... Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. ... Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. ... Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. 2020). Purkinje neuron network (Zang et al. ...
Purkinje cells receive two excitatory inputs, parallel fiber (PF) and climbing fiber (CF). This PC circuitry is established by ... Analysis for heterosynaptic competition between parallel and climbing fiber in mature Purkinje cells. Research Project ... Calcineurin B1 subunit is essential for climbing fiber mono-innervation and inhibitory synapse formation in cerebellar Purkinje ... Territories of heterologous inputs onto Purkinje cell dendrites are segregated by mGluR1-dependent parallel fiber synapse ...
Fibers that show a high resting potential cannot be excited except by depolarizing stimuli strong enough to move the membrane ... Fibers that show a low resting potential are more easily excited and may show rhythmic activity sustained by afterpotentials ... The membrane potential of these fibers can be switched from -50 mV to -90 mV by a hyperpolarizing current pulse and from -90 mV ... A reduction in potassium conductance causes the fiber to depolarize from -90 mV to -50 mV because of the presence of an inward ...
We studied the mechanism and dynamics of recovery from depression at the climbing fiber to Purkinje cell synapse, where marked ... Climbing fibers are well suited to studies of recovery from depression because they display little, if any, facilitation (even ... Calcium dependence and recovery kinetics of presynaptic depression at the climbing fiber to Purkinje cell synapse.. @article{ ... We studied the mechanism and dynamics of recovery from depression at the climbing fiber to Purkinje… CONTINUE READING ...
  • Purkinje cells are large neurons located in the cerebellum. (wisegeek.com)
  • Purkyne, spelled alternatively at Purkinje, also discovered Purkinje cells , which are large neurons located in the cerebellum . (wisegeek.com)
  • Here we report that LTD at the climbing fiber-Purkinje cell synapse in rat cerebellum was not associated with changes in a synaptic cleft glutamate transient, indicating that this type of LTD is most likely expressed postsynaptically. (nih.gov)
  • Dendrites of Purkinje cells (PCs) are arborized in the parasagittal plane of the cerebellum, and consist of two compartments, distal and proximal, that differ in the origin of their inputs as well as in the mode of innervation. (jneurosci.org)
  • The uniquely powerful excitatory synaptic action of a single climbing fiber on a Purkinje cell in the cerebellum of the cat was tested during the intense and prolonged inhibitory action produced by the parallel fiber, basket and stellate cell system. (eurekamag.com)
  • The contactin-related protein FAR-2 defines purkinje cell clusters and labels subpopulations of climbing fibers in the developing cerebellum. (uzh.ch)
  • This protein is expressed by subpopulations of Purkinje cells in the chicken cerebellum and FAR-2-positive clusters of these neurons alternate with FAR-2-negative clusters in both tangential dimensions of the cerebellar cortex. (uzh.ch)
  • Presynaptic origin of paired-pulse depression at climbing fibre-Purkinje cell synapses in the rat cerebellum. (semanticscholar.org)
  • Objective: To study and compare the histomorphological changes induced by second generation (2G), third generation (3G) and fourth generation (4G) mobile phone electromagnetic fields on the organization of Purkinje cell layer of rat cerebellum. (thefreedictionary.com)
  • G-CSF receptors are expressed in pyramidal neurons in the cortex (mainly layers II/III and V), the Purkinje cell layer of the cerebellum, the hippocampus (hilus and CA3 field), the entorhinal cortex and the olfactory bulb. (thefreedictionary.com)
  • Andersen, "Reduction of Purkinje cell volume in cerebellum of alcoholics," Brain Research, vol. (thefreedictionary.com)
  • Specifically, we analyzed conditioned blink responses, which are known to be dependent on the cerebellum, while stimulating the climbing fibers at different frequencies. (eneuro.org)
  • SIGNIFICANCE STATEMENT The glutamate receptor GluD2 expressed at parallel fiber (PF)-Purkinje cell (PC) synapses regulates the formation and maintenance of the synapses. (jneurosci.org)
  • A recently discovered postsynaptic form of LTP at cerebellar parallel fiber (PF)-Purkinje cell (PC) synapses provides a reversal mechanism for PF-LTD and enables a fresh look at the implications of bidirectional plasticity in a brain structure that is particularly suitable to correlate cellular to behavioral learning events. (nih.gov)
  • At the cellular level, we show that Ca V3.1 channels are required for long-term potentiation at parallel fiber-Purkinje cell synapses. (eur.nl)
  • Adaptation of granule cell to Purkinje cell synapses to high-frequency transmission. (semanticscholar.org)
  • A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. (plos.org)
  • Learning was proposed to occur as long-term synaptic plasticity at the parallel fiber - Purkinje cell synapses in the form of long-term depression under instructive control by climbing fibers. (plos.org)
  • In this study, we present a technique for modeling the mesh structure of Purkinje fibers semiautomatically using an extended L-system. (go.jp)
  • The Purkinje fibers are specialized conducting fibers composed of electrically excitable cells. (wikipedia.org)
  • Purkinje fibers take up stain differently from the surrounding muscle cells because of having relatively fewer myofibrils than other cardiac cells. (wikipedia.org)
  • The Purkinje fibers do not have any known role in setting heart rate unless the SA node is compromised (when they can act as pacemaker cells). (wikipedia.org)
  • When an electrical impulse is sent along the Purkinje fibers, it is rapidly relayed to the ventricular cells on both sides of the heart. (wisegeek.com)
  • These special cells found in the Purkinje fibers are able to conduct nerve signals more rapidly than other muscle cells in the heart and so are crucial for the normal beating of the heart. (reference.com)
  • Although injured axons usually do not regenerate in the adult CNS, parallel fibers (PFs) regenerate synaptic connections onto cerebellar Purkinje cells (PCs). (jneurosci.org)
  • Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex, and they occupy a central position in cerebellar circuitry. (jneurosci.org)
  • CaV3.1 T-type channels are abundant at the cerebellar synapse between parallel fibers and Purkinje cells where they contribute to synaptic depolarization. (eur.nl)
  • Climbing fibers (CFs) provide instructive signals driving cerebellar learning, but mechanisms causing the variable CF responses in Purkinje cells (PCs) are not fully understood. (yale.edu)
  • Purkinje cells receive two excitatory inputs, parallel fiber (PF) and climbing fiber (CF). This PC circuitry is established by heterosynaptic competition between PF and CF, fueled by glutamate receptor GluRδ2 and voltage-gated calcium ion channel Cav2.1, respectively. (nii.ac.jp)
  • Effects of low [K+]o on the electrical activity of human cardiac ventricular and Purkinje cells. (semanticscholar.org)
  • Purkinje cells receive inputs (climbing fibers) from the inferior olive, and they send their axons (inhibitory) to the cerebellar and vestibular nuclei. (thefreedictionary.com)
  • A single row of large flask-shaped cells (Purkinje cells) lying between molecular and granular layers of the cerebellar cortex. (thefreedictionary.com)
  • Purkinje cells - large nerve cells of the cerebellar cortex with a piriform cell body and dendrites arranged in a plane transverse to the folium. (thefreedictionary.com)
  • Purkinje fibers - interlacing fibers formed of modified cardiac muscle cells that are the terminal ramifications of the conducting system of the heart found beneath the endocardium of the ventricles. (thefreedictionary.com)
  • Purkinje layer - the layer of Purkinje cells between the molecular and granular layers of the cerebellar cortex. (thefreedictionary.com)
  • Histopathogical findings include widening of the molecular layer of the cerebellar cortex with replacement by abnormal ganglion cells, absence of the Purkinje cell layer, and hypertrophy of the granular cell layer. (thefreedictionary.com)
  • It has been known for a long time that GABAergic Purkinje cells in the cerebellar cortex, as well as their target neurons in the cerebellar nuclei, are spontaneously active. (eneuro.org)
  • It has been shown that input from climbing fibers originating in the inferior olive controls the spontaneous activity in Purkinje cells. (eneuro.org)
  • While blocking climbing fiber input to the Purkinje cells causes a dramatic increase in the firing rate, increased climbing fiber activity results in reduced Purkinje cell activity. (eneuro.org)
  • At 4 Hz, Purkinje cells were completely silenced. (eneuro.org)
  • Purkinje cells, in the cerebellar cortex, have a spontaneous activity that is regulated by climbing fiber input from the inferior olive. (eneuro.org)
  • These results demonstrate that cerebellar function is crucially dependent on normal levels of spontaneous activity in Purkinje cells. (eneuro.org)
  • Using Pcp4 -null mice and acquired cardiomyopathy models, we determined that reduced expression of PCP4 is associated with CaMKII activation, abnormal electrophysiology, dysregulated intracellular calcium handling, and proarrhythmic behavior in isolated Purkinje cells. (jci.org)
  • Here we show that GLAST, a major glutamate transporter in the cerebellar cortex, is essential for synaptic wrapping by Bergmann glia and synaptic wiring on Purkinje cells (PCs) by parallel fibers (PFs) and climbing fibers (CFs). (pnas.org)
  • Here we report that Bergmann glia (BG), specialized cerebellar astrocytes that thoroughly enwrap Purkinje cells (PCs), are essential for synaptic organization in PCs through the action of the l -glutamate/ l -aspartate transporter (GLAST). (pnas.org)
  • Yet, it is not clear whether altering the final placement of Purkinje cells affects the assembly of circuits into topographic zones. (frontiersin.org)
  • Despite the abnormal placement of more than 95% of Purkinje cells in scrambler mice, the complementary relationship between molecularly distinct Purkinje cell zones is maintained, and consequently, afferents are targeted into topographic circuits. (frontiersin.org)
  • If Purkinje cell zones do provide the platform for zone assembly, then incoming afferents should be sensitive to the dispersal of Purkinje cells into their final locations. (frontiersin.org)
  • To investigate the influence of cefuroxime sodium (CS) on the electrophysiological function of cerebellar Purkinje cells (PCs) in Sprague-Dawley rats . (bvsalud.org)
  • We propose that RyR3 expression in P-cells plays a role in the stability of electric function of Purkinje fibers. (elsevier.com)
  • Developmental Rewiring between Cerebellar Climbing Fibers and Purkinje Cells Begins with Positive Feedback Synapse Addition. (bioportfolio.com)
  • particular in the selective destruction of cerebellar Purkinje cells, between ABV and BDV infections of the brains of Tissue Culture birds and mammals, respectively ( 11 ). (cdc.gov)
  • Tsien, R. W. Effects of epinephrine on the pacemaker current of cardiac Purkinje fibers. (springer.com)
  • During the ventricular contraction portion of the cardiac cycle, the Purkinje fibers carry the contraction impulse from both the left and right bundle branch to the myocardium of the ventricles. (wikipedia.org)
  • The Purkinje fibers are located in the ventricular walls of the heart, just beneath the endocardium and conduct excitation from the right and left bundle branches to the ventricular myocardium. (go.jp)
  • Purkinje fibers are usually thicker than the contractile fibers of the myocardium and are rich in mitochondria and glycogen. (thefreedictionary.com)
  • It is possible to take this momentum back to Purkinje fibers along the vessels of the myocardium. (wikipedia.org)
  • Methods Gene expression of CR channels was measured by qPCR in Purkinje fibers and myocardium of adult Yucatan pig hearts. (elsevier.com)
  • Results RyR2 gene expression was identical in Purkinje fibers and myocardium (6 hearts) while RyR3 and InsP 3 R gene expressions were, respectively, 100 and 16 times larger in the Purkinje fibers. (elsevier.com)
  • any of the specialized cardiac muscle fibers forming a network in the ventricular walls that conduct electric impulses responsible for the contractions of the ventricles. (dictionary.com)
  • Any of the specialized cardiac muscle fibers, part of the impulse-conducting network of the heart, that rapidly transmit impulses from the atrioventricular node to the ventricles. (dictionary.com)
  • Effects of membrane potential on the capacitance of skeletal muscle fibers. (springer.com)
  • Purkinje fibers are specialized muscle fibers found in the heart. (wisegeek.com)
  • Purkinje fibers refer to specialized muscle fibers in the heart that are located beneath the innermost layer of the heart, known as the endocardium. (wisegeek.com)
  • Demonstrating purkinje fibers, the modified cardiac muscle fibers which occur on the periphery of the cell. (wardsci.com)
  • Specialized muscle fibers that conduct the cardiac impulse from the AV bundle into the ventricular walls. (washington.edu)
  • Question 22 of 60 1.67/ 1.667 Points Cardiac muscle fibers are connected with each other by A. desmosomes. (bartleby.com)
  • Action potential duration alternans in dog Purkinje and ventricular muscle fibers. (meta.org)
  • An abrupt shortening of cycle length causes action potential duration (APD) alternation in both canine Purkinje (P) and ventricular (V) muscle fibers. (meta.org)
  • Erlanger, in studying the physiology of Purkinje tissue, observed, after numerous trials, a case in which there seemed to be independent movement of false tendons. (docme.ru)
  • The Purkinje fibers come off of the bundle branches to bring the impulse deep into the muscle tissue. (wisegeek.com)
  • Picture something like a length of yarn (the bundle branch) with fibers splitting off to the sides and from the ends (the purkinje fibers). (wisegeek.com)
  • Purkinje fibers are special fibers that are located in the atrioventricular, or AV, bundle of the heart. (reference.com)
  • It sends impulses down the septum through the AV bundle branches to the Purkinje fibers. (reference.com)
  • We designed a generating rule based on observations of the photograph of Purkinje fibers and manually specified three terminal positions on a three-dimensional (3D) heart model: those of the right bundle branch, the anterior fascicle, and the left posterior fascicle of the left branch. (go.jp)
  • Receive action potential propogated by the bundle of His and and then in turn connect to the Purkinje fibers. (google.com)
  • After a delay, the stimulus is conducted through the bundle of His to the Purkinje fibers and the endocardium at the apex of the heart, then finally to the ventricular epicardium. (wikidoc.org)
  • Conducting fibers that connect the AV node through the myocardial interventricular septum to the left and right bundle branches. (flashcardmachine.com)
  • The fibers of the Bundle of His allow electrical conduction to occur more easily and quickly than typical cardiac muscle. (bionity.com)
  • Together, the bundle branches and Purkinje network comprise the ventricular conduction system. (bionity.com)
  • 2007. Houghton Mifflin Company 23 Oct. 2016 http://medical-dictionary.thefreedictionary.com/Purkinje+fiber Brooker, Graham (January 1, 2019), Segil, Jacob (ed. (wikipedia.org)
  • Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. (wikipedia.org)
  • These fibers, also known as subendocardial branches , are located beneath the endocardium , which is the innermost layer of the heart. (wisegeek.com)
  • In GLAST-knockout mice, dendritic innervation by the main ascending climbing fiber (CF) branch was significantly weakened, whereas the transverse branch, which is thin and nonsynaptogenic in control mice, was transformed into thick and synaptogenic branches. (pnas.org)
  • The fascicular branches then lead to the Purkinje fibers which innervate the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval. (bionity.com)
  • For example, cerebellar Purkinje cell nucleoli were used as counting units to obtain unbiased (fractionator) estimates of the number of Purkinje neurons in adult mammalian cerebella. (thefreedictionary.com)
  • TTBK2 and primary cilia are essential for the connectivity and survival of cerebellar Purkinje neurons. (bioportfolio.com)
  • Colatsky, T. J. Voltage clamp measurements of sodium channel properties in rabbit cardiac Purkinje fibres. (springer.com)
  • Sodium channels in rabbit cardiac Purkinje fibres. (springer.com)
  • Weidmann, S. The electrical constants of Purkinje fibres. (springer.com)
  • Is potassium conductance of cardiac Purkinje fibres controlled by [Ca2+]i? (semanticscholar.org)
  • Myofibrillar M-bands developed an earlier stage in Purkinje fibres than in ordinary myocytes. (thefreedictionary.com)
  • Antiarrhythmic effects of nicorandil on canine cardiac Purkinje fibers. (nih.gov)
  • Two levels of resting potential in canine cardiac Purkinje fibers exposed to sodium-free solutions. (semanticscholar.org)
  • Canine cardiac Purkinje fibers exposed to sodium-free solutions containing 16 mM CaCl2, 20 mM tetraethylammonium chloride, 108 mM tetramethylammonium chloride, and 2.7 mM KCl may be quiescent at a resting potential of either -50 mV or -90 mV. (semanticscholar.org)
  • Purkinje network - the network formed by Purkinje fibers beneath the endocardium. (thefreedictionary.com)
  • It is well established that the climbing fiber (CF) input to a cerebellar Purkinje cell (PC) can exert a controlling influence on the background simple spike (SS) activity of the cell, in that repetitive stimulation of CFs causes a decrease in SS activity, and removal or inactivation of CFs is followed by a rise in activity. (jneurosci.org)
  • Moreover, basal simple spike discharge of the Purkinje cell in KO mice is modified. (eur.nl)
  • Furthermore, FAR-2 is also expressed by one type of Purkinje cell afferents, namely, the climbing fibers, and different subpopulations of these axons show distinct levels of FAR-2 expression. (uzh.ch)
  • Journal Article] Territories of heterologous inputs onto Purkinje cell dendrites are segregated by mGluR1-dependent parallel fiber synapse elimination. (nii.ac.jp)
  • Calcium dependence and recovery kinetics of presynaptic depression at the climbing fiber to Purkinje cell synapse. (semanticscholar.org)
  • Intracellular pH and cell-to-cell transmission in sheep Purkinje fibers // Biophys. (thefreedictionary.com)
  • FMRP is known to help regulate synapse function, so it may contribute to the abnormalities seen in Purkinje cell functioning in TSC. (thefreedictionary.com)
  • Purkinje cell dendrites grow in alignment with Bergmann glia. (thefreedictionary.com)
  • 2001) Onset of ataxia and Purkinje cell loss in PrP null mice inversely correlated with Dpl level in brain. (thefreedictionary.com)
  • Impairment of LTD and cerebellar leaning by Purkinje cell specific ablation of GMPC -dependent protein kinasa I. (thefreedictionary.com)
  • Ischemia increases Purkinje cell automaticity, and the spontaneous firing of these fibers triggers polymorphic VT or VF. (thefreedictionary.com)
  • Increased calbindin-D28K immunoreactivity in rat cerebellar Purkinje cell with excitatory amino acids agonists is not dependent on protein synthesis. (thefreedictionary.com)
  • Here we examine the relation between climbing fiber stimulation frequency and Purkinje cell activity in unanesthetized decerebrated ferrets. (eneuro.org)
  • The results revealed a gradual suppression of Purkinje cell activity, starting at climbing fiber stimulation frequencies as low as 0.5 Hz. (eneuro.org)
  • Here we show that stimulating climbing fibers result in a frequency dependent suppression of Purkinje cell activity. (eneuro.org)
  • Here, through transcriptional profiling of genetically labeled cardiomyocytes, we identified expression of Purkinje cell protein-4 ( Pcp4 ), a putative regulator of calmodulin and Ca 2+ /calmodulin-dependent kinase II (CaMKII) signaling, exclusively within the His-Purkinje network. (jci.org)
  • Together, these results demonstrate that PCP4 regulates cardiac excitability through both Purkinje cell-autonomous and central mechanisms and identify this modulator of CaMKII signaling as a potential arrhythmia-susceptibility candidate. (jci.org)
  • Importantly, developing Purkinje cell zones are thought to provide the framework upon which afferent circuitry is organized. (frontiersin.org)
  • spontaneous mutants that have severe Purkinje cell ectopia due to the loss of reelin-disabled1 signaling. (frontiersin.org)
  • We used immunohistochemistry and neural tracing to determine whether displacement of Purkinje cell zones into ectopic positions triggers defects in zonal connectivity within sensory-motor circuits. (frontiersin.org)
  • These data suggest that although loss of disabled1 distorts the Purkinje cell map, its absence does not obstruct the formation of zonal circuits. (frontiersin.org)
  • These findings support the hypothesis that Purkinje cell zones play an essential role in establishing afferent topography. (frontiersin.org)
  • ZebrinII zones are integrated into a broader map where they have an intricate relationship to the expression of several other Purkinje cell proteins. (frontiersin.org)
  • Zones are defined not only by Purkinje cell expression but also by the organization of their axonal inputs. (frontiersin.org)
  • Although we are beginning to understand how Purkinje cell zones form, our understanding of how the cerebellar cortical circuit is assembled into zonal connectivity patterns remains unclear. (frontiersin.org)
  • Here, we test the hypothesis that altering Purkinje cell placement will disrupt the assembly of circuits into distinct sagittal zones. (frontiersin.org)
  • The whole- cell patch-clamp technique was used to record inward current and action potential of PCs on cerebellar slices, as well as the long-term depression (LTD) of excitatory postsynaptic current (EPSC) in PCs induced by low-frequency stimulation of parallel fiber (PF). (bvsalud.org)
  • Climbing fiber (CF) triggered complex spikes (CS) are massive depolarization bursts in the cerebellar Purkinje cell (PC), showing several high frequency spikelet components (±600 Hz). (frontiersin.org)
  • The Purkinje cell (PC) is the main point of converging pathways and the sole output neuron of the cerebellar cortex. (frontiersin.org)
  • During postnatal development, cerebellar climbing fibers alter their innervation strengths onto supernumerary Purkinje cell targets, generating a one-to-few connectivity pattern in adulthood. (bioportfolio.com)
  • Intra- and extracellular K+ and Na+ activities and resting membrane potential in sheep cardiac purkinje strands. (semanticscholar.org)
  • Effects of low-chloride solutions on action potentials of sheep cardiac Purkinje fibers. (rupress.org)
  • Recently, anatomists succeeded in photographing the Purkinje fibers of a sheep, which clearly showed the mesh structure of the Purkinje fibers. (go.jp)
  • The electrophysiological effects mediated by beta 2-adrenoceptor stimulation were studied in sheep cardiac Purkinje fibers. (meta.org)
  • We used intracellular microelectrodes to study the effects of histamine on both normal and abnormal automaticity in sheep Purkinje fibers. (unifi.it)
  • Purkinje fibers allow the heart's conduction system to create synchronized contractions of its ventricles, and are essential for maintaining a consistent heart rhythm. (wikipedia.org)
  • Conduction velocity was determined in vitro by measuring the conduction time between action potentials recorded from two Purkinje fibers located about 6 mm apart along the length of free running portions of the ventricular conduction system, the false tendons. (asahq.org)
  • Further histologic examination reveals that these fibers are split in ventricles walls. (wikipedia.org)
  • The blood vessels were analyzed by light microscopy using four different staining techniques in transverse sections taken from the upper, middle, and lower segments of the anterior part of the interventricular region and the adjacent parts of the right and left ventricles containing epicardial nerves and the endocardial peripheral parts of the Purkinje fibers. (vuzv.cz)
  • Purkinje system - terminal ramifications in the ventricles of the specialized conducting system of the heart. (thefreedictionary.com)
  • Network of nerve fibers throughout the ventricles. (smore.com)
  • The electrical origin of atrial Purkinje fibers arrives from the sinoatrial node. (wikipedia.org)
  • Early after-depolarization occurred in 6/7 fibers exposed to droperidol and 1/8 fibers exposed to ondansetron. (biomedsearch.com)
  • The fibers were discovered by Jan Evangelista Purkyne, a Czech physiologist, in 1837. (reference.com)
  • Purkinje fibers are stretched along heart muscle tissue beginning at the atrioventricular node . (wisegeek.com)
  • Since the sinus node is the normal pacer, latent pacing sites at the AV junction or ventricular Purkinje fibers are driven to low resting potentials by the sinus node and have lower rates of normal automaticity (Abraham, 1992). (thefreedictionary.com)
  • Purkinje fibers were named after a Czechoslovakian anatomist named Jan Evangelista Purkyne. (wisegeek.com)
  • The pacemaker potential in Purkinje fibers is generated by a slow fall in potassium current which allows the inward background currents to depolarize the membrane. (sciencemag.org)
  • Epinephrine promotes spontaneous activity in cardiac Purkinje fibers through its action on the pacemaker potassium current ( i K K2 ). (rupress.org)
  • This histology slide shows purkinje fibers in H&E stained cardiac muscle. (histology-world.com)
  • In Purkinje fibers one pharmacologically distinguishable alpha 1-adrenoceptor subtype (alpha 1B) sensitive to the noncompetitive antagonist chloroethylcholinidine mediates decreases in automaticity. (asahq.org)
  • Antiarrhythmic efficacy of nicorandil (SG-75) (1-100 microM), a coronary vasodilator, was investigated electrophysiologically with regard to the action potentials of canine Purkinje fibers. (nih.gov)
  • Effects of 1 microM verapamil on action potentials of Purkinje fibers from normal and infarcted zones (NZ and IZ) were studied using conventional microelectrode techniques. (aspetjournals.org)
  • Epinephrine (0.2-5.0 microM) transiently decreased Purkinje conduction velocity in a dose-related manner by as much as 33% (at 5 microM epinephrine with 0.86 mM (2.8%) halothane). (asahq.org)
  • Purkinje fibers, driven at 1 Hz, were exposed to increasing concentrations (from 0.001 to 10 microm) of droperidol (n = 7) or ondansetron (n = 8) at 30 min intervals at 36.5 degrees C. Other fibers were exposed to a constant droperidol concentration (0.1 microm) alone (n = 7) or together with the same increasing concentrations of ondansetron (n = 6). (biomedsearch.com)
  • Voltage clamp technique in mammalian cardiac fibers. (springer.com)
  • By the collision technique it is shown that the same climbing fiber is activated by inferior olive and juxtafastigial stimulation. (eurekamag.com)
  • and (ii) the very strong connection by the climbing fiber (CF), originating in the Inferior Olive (IO) and branching over the PC dendrite proximal part. (frontiersin.org)
  • Purkinje fibers are named after a Czech (country in Western Europe) scientist Jan Evangelista Purkyně, who discovered them in 1839. (wikipedia.org)
  • Purkinje conduction - conduction of the cardiac impulse through the Purkinje system. (thefreedictionary.com)
  • These fibers distribute the impulse to the ventricular muscle. (bionity.com)
  • Mechanisms of action of lidocaine and quinidine on action potential duration in rabbit cardiac Purkinje fibers. (ahajournals.org)
  • Another alpha 1 subtype (alpha 1A), sensitive to the competitive antagonist WB4101, increases spontaneous rate and action potential duration by a mechanism thought to involve hydrolysis of membrane phosphoinositides by phospholipase C. This study examined the dose-response relation and receptor-effector mechanisms underlying depression of conduction in canine Purkinje fibers by epinephrine with halothane. (asahq.org)
  • Histamine, dimaprit and 4-methylhistamine caused a similar reduction of the action potential duration in driven Purkinje fibers. (unifi.it)
  • Both ondansetron and droperidol prolong AP duration in Purkinje fibers, droperidol being 10 times more potent than ondansetron. (biomedsearch.com)
  • Chapter 7 - Regeneration of Cardiac Muscle and Hematopoietic Tissues", Regenerative Biology and Medicine (Second Edition), San Diego: Academic Press, pp. 161-182, doi:10.1016/b978-0-12-384860-4.00007-1, ISBN 978-0-12-384860-4, retrieved November 13, 2020 "Purkinje fiber. (wikipedia.org)
  • The excitatory action of a climbing fiber synapse is greatly depressed immediately after a preceding activation and recovery takes hundreds of milliseconds. (eurekamag.com)
  • The electrical constants of a crustacean nerve fiber. (springer.com)
  • The Purkinje fibers are further specialized to rapidly conduct impulses (having numerous fast voltage-gated sodium channels and mitochondria, and fewer myofibrils, than the surrounding muscle tissue). (wikipedia.org)
  • Methods and Results: 6 patients with Acute Myocardial Infarction (5 AW/ 1 LW) and Purkinje Triggered ventricular arrhythmias refractory to conventional anti-arrhythmics were treated with intravenous Fosphenytoin (600 mg-1 gm) before considering RFA. (manipal.edu)
  • Additionally, from a total of 33 analyzed ventricular complexes of Purkinje fibers small blood vessels located in their proximity were identified in only two cases. (vuzv.cz)
  • In contrast, similar blood vessels are rarely present in the vicinity of the Purkinje fibers. (vuzv.cz)
  • When a Purkinje fiber does fire, it is called a premature ventricular contraction or PVC, or in other situations can be a ventricular escape. (wikipedia.org)
  • These fibers facilitate rapid conduction of impulses for contraction. (wardsci.com)
  • A WB 4101-sensitive alpha-1 adrenergic receptor subtype modulates repolarization in canine Purkinje fibers. (aspetjournals.org)
  • We used standard microelectrode techniques to study alpha-1 adrenergic modulation of repolarization in canine Purkinje fibers. (aspetjournals.org)
  • U' waves are thought to represent repolarization of the Purkinje fibers . (wikipedia.org)
  • The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. (plos.org)
  • In these models, parameter adaptation was driven by the correlation of a sensory error signal with a motor command signal, which were proposed to correspond to climbing fiber and mossy fiber signals, respectively. (plos.org)
  • The Purkinje fibers can be found in the ventricle walls, which are at the bottom of the heart in an area called the subendocardium. (reference.com)
  • However, the Purkinje fibers do not actually set the heart rate. (reference.com)
  • Actions of verapamil on Purkinje fibers from normal and infarcted heart tissues. (aspetjournals.org)
  • On the comparative vascularity of heart muscle and of the purkinje fibers. (docme.ru)
  • If the Purkinje fibers represent tissue specialized for the same type of contractility as heart muscle, one would expect them to have a vascular supply equal in abundance to that of heart muscle. (docme.ru)
  • We have, in this study, compared the vascularity of the Purkinje fibers and of heart muscle. (docme.ru)