Disease relevance of Purkinje Fibers

• Cesium chloride (5 to 20 mM), which induces triggered arrhythmias in the intact dog, was used to induce EADs in isolated canine Purkinje fibers, and these were studied by microelectrode techniques [1].
• We studied automaticity induced at normal and low membrane potentials, conduction in normal and K+-depolarized Purkinje fibers, and triggered activity induced by ouabain and by experimental myocardial infarction [2].
• In Purkinje fibers from dogs treated with pertussis toxin, NE no longer induced a CEC-sensitive decrease in automaticity [3].
• CO2-induced acidosis (20% CO2, pH 6.6) may alter the repolarization phase of the action potential in dog Purkinje fibers, presumably because it decreases potassium conductance [4].
• We determined the effects of acetylcholine on automaticity of isolated cardiac Purkinje fibers from neonatal and adult dogs and on the idioventricular rhythm of adult dogs with complete atrioventricular block [5].

Psychiatry related information on Purkinje Fibers

• Inducing of automatism of Purkinje fibers with dibutyryl 3', 5' cyclic AMP [6].

High impact information on Purkinje Fibers

• Purkinje fibers share common lineage with cardiomyocytes not neural cells [7]
• Two independent markers reveal defects in the formation of ventricular Purkinje fibers [8].
• Surprisingly, the cellular expression of connexin40, the major gap junction isoform of Purkinje fibers and a putative Nkx2-5 target, is unaffected, consistent with normal conduction times through the His-Purkinje system measured in vivo [9].
• The dynamic response of squared conduction velocity, theta 2, to repetitive stimulation in canine Purkinje fibers with quinidine was studied using a double-microelectrode technique [10].
• Immunofluorescence labeling of sheep Purkinje fibers show that the ryanodine receptor is confined to discrete foci while the SR-Ca(2+)-ATPase is distributed in a continuous network-like structure present at the periphery as well as throughout interior regions of these myofibers [11].
• Beta-adrenergic augmentation of flecainide-induced conduction slowing in canine Purkinje fibers [12].

Chemical compound and disease context of Purkinje Fibers

• We compared the effects of lidocaine, 2 X 10(-5) M, on transmembrane resting and action potentials of Purkinje fibers on the endocardial surface of 24- to 72-hour-old myocardial infarcts in dogs with its actions and subendocardial Purkinje fibers in normal hearts [13].
• Effects of intracoronary potassium chloride on electrograms of canine Purkinje fibers in six-hour- to four-week-old myocardial infarcts. An indication of time-dependent changes in collateral blood flow [14].
• Studies were performed on canine cardiac Purkinje fibers to evaluate the effects of acidosis and bicarbonate (HCO3) on action potential repolarization [15].
• The effect of metabolic inhibitors on strophanthidin-induced arrhythmias and contracture in cardiac purkinje fibers [16].
• Effects of epinephrine on automaticity and the incidence of arrhythmias in Purkinje fibers surviving myocardial infarction [17].

Biological context of Purkinje Fibers

• Clofilium markedly prolonged action potential duration in Purkinje fibers but not in ventricular muscle cells, and eventually, bradycardia-dependent EADs and triggered activity were elicited [18].
• The adult conduction system (CS) comprises the sinoatrial (SAN), and atrioventricular (AVN) nodes, the atrioventricular bundle (AVB), the bundle branches and the peripheral Purkinje fibers, each of which display distinct functional properties and distinct profile of gene expression [19].
• Blood superfusion techniques were used to study the effects of verapamil on the body surface electrocardiogram and blood pressure of intact, anesthetized dogs as well as transmembrane action potential characteristics of isolated Purkinje fibers [20].
• Occurrence of binding sites for [125I] ANP in the myocardium but not in Purkinje fibers of the bovine heart [21].
• The voltage- and frequency-dependent blocking actions of disopyramide were assessed in canine Purkinje fibers within the framework of concentrations, membrane potentials, and heart rates which have relevance to the therapeutic actions of this drug [22].

Anatomical context of Purkinje Fibers

• In this study microelectrode techniques were used to assess the electrophysiologic effects of milrinone in canine false tendons homogeneously superfused with either normal or high-K Tyrode's solution and in Purkinje fibers mounted in a three-compartment chamber in which the central segment was depressed with an "ischemic" solution [23].
• BACKGROUND: The localization of dystrophin at the sarcolemma of cardiac skeletal fibers and cardiac Purkinje fibers has been described [24].
• Amrinone induced slight increases in right atrial rate with no changes in electrophysiological properties of the cat papillary muscle or dog Purkinje fibers [25].
• The present study was performed to determine whether lysophosphatidylcholine (LPC), at concentrations comparable to those present in ischemic myocardium, can induce delayed afterdepolarizations and/or triggered activity in normoxic canine Purkinje fibers [26].
• Recainam had no significant effect on the sinoatrial node, but it depressed phase 4 depolarization in isoproterenol-induced automaticity in Purkinje fibers [27].

Associations of Purkinje Fibers with chemical compounds

• Characterization of concentration- and use-dependent effects of quinidine from conduction delay and declining conduction velocity in canine Purkinje fibers [10].
• Isolated canine Purkinje fibers were superfused with 2 X 10(7)M ouabain until delayed afterdepolarizations occurred and attained an amplitude of 5 mV at a paced cycle length of 500 msec [28].
• The inotropic effects of strophanthidin in Purkinje fibers and the sodium pump [29].
• Enhancement by norepinephrine of automaticity in sheep cardiac Purkinje fibers exposed to hypoxic glucose-free Tyrode's solution: a role for alpha-adrenoceptors [30]?
• In quiescent normal and infarcted preparations, a low concentration of caffeine (0.5 mM) differentially induced DADs in ischemic but not in normal Purkinje fibers, increased the amplitude of existing DADs, and brought subthreshold DADs to threshold potential that caused triggered activity [31].

Gene context of Purkinje Fibers

• Purkinje fibers express characteristic patterns of gap junctional connexins (Cx43, Cx40 and Cx45) [32], [33],[34].
• Conversely, pressure-overload in the ventricle by conotruncal banding results in a significant expansion of endocardial ECE1 expression and Cx40-positive putative Purkinje fibers [35].
• Collectively, the results provide the first sing of a possible functional interaction between ANKRD1 and CASQ2 and suggest a potentially novel role for both proteins in cardiac Purkinje fibers [36].
• Dystrophin was present at the periphery of cardiocytes and cardiac Purkinje fibers as well as in transverse T tubules but was absent or faintly expressed in intercalated disks [24].
• CONCLUSIONS: This first localization of utrophin in normal heart (in Purkinje fibers, transverse tubules, and intercalated disks) showed a distinct subcellular localization of this protein with dystrophin, suggesting an important function of this protein in intercellular communication [24].
• The nodal tissues never exhibited immunoreactions for ANP or BNP, whereas Purkinje fibers of the atrioventricular junctional tissue, bundle branches, and the peripheral Purkinje fiber network exhibited specific immunoreactivity [37].

Analytical, diagnostic and therapeutic context of Purkinje Fibers

• These antisera detect approximately 400,000-d immunoreactive band or bands on Western blot in normal heart and Purkinje fibers but not in DMD heart [38].
• The interaction of Bay k 8644 with calcium channels in calf Purkinje fibers was studied using the two-microelectrode voltage clamp technique [39].
• To determine whether differences in connexin expression may account, in part, for the characteristic conduction properties of Purkinje fibers and ventricular muscle, we assessed the amounts of mRNA for two connexins, Cx40 and Cx43, in these tissues obtained from canine hearts by Northern blot analysis and in situ hybridization [40].
• One day after ligation of the canine anterior descending coronary artery, clofilium, a long-acting class III antiarrhythmic agent, was studied for its effects on normal and ischemic Purkinje fibers [41].
• The effects of lidocaine on the canine ECG and electrophysiologic properties of Purkinje fibers [42].

References