scholarly journals Potential Roles of Purkinje Fibers in Ischemia-Induced Arrhythmias

2020 ◽  
Author(s):  
Teo Puig Walz ◽  
Luca Azzolin ◽  
Lucas Berg ◽  
Enaam Chleilat ◽  
Hermenegild Arevalo
Keyword(s):  
Purkinje Fibers

Electrophysiologic Effects of RS-2135, a New Antiarrhythmic Compound, on Canine Purkinje Fibers

1992 ◽  
Vol 20 (6) ◽  
pp. 955-960 ◽  
Author(s):  
Ryosuke Yorikane ◽  
Toshio Sada ◽  
Hiroyuki Koike
Keyword(s):  
Purkinje Fibers

Differential Effects of Halothane and Isoflurane on Contractile Force and Calcium Transients in Cardiac Purkinje Fibers

1994 ◽  
Vol 80 (6) ◽  
pp. 1360-1368 ◽  
Author(s):  
David F. Stowe ◽  
Juraj Sprung ◽  
Lawrence A. Turner ◽  
John P. Kampine ◽  
Zeljko J. Bosnjak
Keyword(s):  
Contractile Force ◽  
Calcium Transients ◽  
Purkinje Fibers ◽  
Differential Effects ◽  
Cardiac Purkinje Fibers

Basis for tetrodotoxin and lidocaine effects on action potentials in dog ventricular myocytes

1988 ◽  
Vol 254 (6) ◽  
pp. H1157-H1166 ◽  
Author(s):  
J. A. Wasserstrom ◽  
J. J. Salata
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Ventricular Myocytes ◽  
Ionic Currents ◽  
Detectable Effect ◽  
Na Channel ◽  
Na Current ◽  
Voltage Range ◽  
Purkinje Fibers ◽  
Ventricular Cells

We studied the effects of tetrodotoxin (TTX) and lidocaine on transmembrane action potentials and ionic currents in dog isolated ventricular myocytes. TTX (0.1-1 x 10(-5) M) and lidocaine (0.5-2 x 10(-5) M) decreased action potential duration, but only TTX decreased the maximum rate of depolarization (Vmax). Both TTX (1-2 x 10(-5) M) and lidocaine (2-5 x 10(-5) M) blocked a slowly inactivating toward current in the plateau voltage range. The voltage- and time-dependent characteristics of this current are virtually identical to those described in Purkinje fibers for the slowly inactivating inward Na+ current. In addition, TTX abolished the outward shift in net current at plateau potentials caused by lidocaine alone. Lidocaine had no detectable effect on the slow inward Ca2+ current and the inward K+ current rectifier, Ia. Our results indicate that 1) there is a slowly inactivating inward Na+ current in ventricular cells similar in time, voltage, and TTX sensitivity to that described in Purkinje fibers; 2) both TTX and lidocaine shorten ventricular action potentials by reducing this slowly inactivating Na+ current; 3) lidocaine has no additional actions on other ionic currents that contribute to its ability to abbreviate ventricular action potentials; and 4) although both agents shorten the action potential by the same mechanism, only TTX reduces Vmax. This last point suggests that TTX produces tonic block of Na+ current, whereas lidocaine may produce state-dependent Na+ channel block, namely, blockade of Na+ current only after Na+ channels have already been opened (inactivated-state block).

Ionic mechanisms of electrophysiological properties and repolarization abnormalities in rabbit Purkinje fibers

2011 ◽  
Vol 300 (5) ◽  
pp. H1806-H1813 ◽  
Author(s):  
Alberto Corrias ◽  
Wayne Giles ◽  
Blanca Rodriguez
Keyword(s):  
Purkinje Cells ◽  
Mechanisms Of Action ◽  
Delayed Rectifier ◽  
Pharmacological Interventions ◽  
Drug Induced ◽  
Current Increase ◽  
Detailed Model ◽  
Purkinje Fibers ◽  
Electrophysiological Properties ◽  
Repolarization Abnormalities

Purkinje cells play an important role in drug-induced arrhythmogenesis and are widely used in preclinical drug safety assessments. Repolarization abnormalities such as action potential (AP) prolongation and early afterdeploarizations (EAD) are often observed in vitro upon pharmacological interventions. However, because drugs do not act on only one defined target, it is often difficult to fully explain the mechanisms of action and their potential arrhythmogenicity. Computational models, when appropriately detailed and validated, can be used to gain mechanistic insights into the mechanisms of action of certain drugs. Nevertheless, no model of Purkinje electrophysiology that is able to reproduce characteristic Purkinje responses to drug-induced changes in ionic current conductances such as AP prolongation and EAD generation currently exists. In this study, a novel biophysically detailed model of rabbit Purkinje electrophysiology was developed by integration of data from voltage-clamp and AP experimental recordings. Upon validation, we demonstrate that the model reproduces many key electrophysiological properties of rabbit Purkinje cells. These include: AP morphology and duration, both input resistance and rate dependence properties as well as response to hyperkalemia. Pharmacological interventions such as inward rectifier K+ current and rapid delayed rectifier K+ current block as well as late Na+ current increase result in significant AP changes. However, enhanced L-type Ca2+ current ( iCaL) dominates in EAD genesis in Purkinje fibers. In addition, iCaL inactivation dynamics and intercellular coupling in tissue strongly modulate EAD formation. We conclude that EAD generation in Purkinje cells is mediated by an increase in iCaL and modulated by its inactivation kinetics.

Inhibitory effects of catecholamines in canine cardiac Purkinje fibers

1976 ◽  
Vol 231 (5) ◽  
pp. 1415-1420 ◽  
Author(s):  
P Posner ◽  
EL Farrar ◽  
CR Lambert
Keyword(s):  
Negative Response ◽  
Chronotropic Effect ◽  
Inhibitory Effects ◽  
Purkinje Fibers ◽  
Spontaneous Rate ◽  
Negative Chronotropic Effect ◽  
Cardiac Purkinje Fibers ◽  
Wide Range ◽  
Low Levels

The effect of catecholamines over a wide range of concentrations was studied on 42K uptake and efflux, as well as on spontaneous rate in canine cardiac Purkinje fibers. Low levels of catecholamines (less than 10(-10) M epinephrine; less than 10(-9) M norepinephrine) decreased automaticity. This negative chronotropic effect was blocked by phentolamine and mimicked by phenylephrine. These low levels of epinephrine and norepinephrine also inhibited 42K uptake by Purkinje fibers but had no effect on 42K efflux. The inhibition of 42K uptake was blocked by phentolamine and verapamil and mimicked by phenylephrine. The data indicate an alpha-receptor-mediated negative response of rate and 42K uptake to low levels of catecholamine. The end result is discussed in terms of a competitive increase in the influx of Ca2+ rather than Na+ and an indirect inhibition of the Na+-K+ pump.

scholarly journals Potential arrhythmogenic electrophysiological derangements in canine Purkinje fibers induced by lysophosphoglycerides.

1979 ◽  
Vol 44 (6) ◽  
pp. 822-832 ◽  
Author(s):  
P B Corr ◽  
M E Cain ◽  
F X Witkowski ◽  
D A Price ◽  
B E Sobel
Keyword(s):  
Purkinje Fibers
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