scholarly journals Electrophysiological properties of computational human ventricular cell action potential models under acute ischemic conditions

2017 ◽  
Vol 129 ◽  
pp. 40-52 ◽  
Author(s):  
Sara Dutta ◽  
Ana Mincholé ◽  
T. Alexander Quinn ◽  
Blanca Rodriguez
Keyword(s):  
Action Potential ◽  
Potential Models ◽  
Ventricular Cell ◽  
Electrophysiological Properties

scholarly journals Characterization of the Electrophysiologic Remodeling of Patients With Ischemic Cardiomyopathy by Clinical Measurements and Computer Simulations Coupled With Machine Learning

2021 ◽  
Vol 12 ◽  
Author(s):  
Konstantinos N. Aronis ◽  
Adityo Prakosa ◽  
Teya Bergamaschi ◽  
Ronald D. Berger ◽  
Patrick M. Boyle ◽  
...  
Keyword(s):  
Machine Learning ◽  
Action Potential ◽  
Ischemic Cardiomyopathy ◽  
Model Development ◽  
Tissue Level ◽  
Potential Models ◽  
Electrophysiological Properties ◽  
Infarcted Myocardium ◽  
Clinical Measurements

RationalePatients with ischemic cardiomyopathy (ICMP) are at high risk for malignant arrhythmias, largely due to electrophysiological remodeling of the non-infarcted myocardium. The electrophysiological properties of the non-infarcted myocardium of patients with ICMP remain largely unknown.ObjectivesTo assess the pro-arrhythmic behavior of non-infarcted myocardium in ICMP patients and couple computational simulations with machine learning to establish a methodology for the development of disease-specific action potential models based on clinically measured action potential duration restitution (APDR) data.Methods and ResultsWe enrolled 22 patients undergoing left-sided ablation (10 ICMP) and compared APDRs between ICMP and structurally normal left ventricles (SNLVs). APDRs were clinically assessed with a decremental pacing protocol. Using genetic algorithms (GAs), we constructed populations of action potential models that incorporate the cohort-specific APDRs. The variability in the populations of ICMP and SNLV models was captured by clustering models based on their similarity using unsupervised machine learning. The pro-arrhythmic potential of ICMP and SNLV models was assessed in cell- and tissue-level simulations. Clinical measurements established that ICMP patients have a steeper APDR slope compared to SNLV (by 38%, p < 0.01). In cell-level simulations, APD alternans were induced in ICMP models at a longer cycle length compared to SNLV models (385–400 vs 355 ms). In tissue-level simulations, ICMP models were more susceptible for sustained functional re-entry compared to SNLV models.ConclusionMyocardial remodeling in ICMP patients is manifested as a steeper APDR compared to SNLV, which underlies the greater arrhythmogenic propensity in these patients, as demonstrated by cell- and tissue-level simulations using action potential models developed by GAs from clinical measurements. The methodology presented here captures the uncertainty inherent to GAs model development and provides a blueprint for use in future studies aimed at evaluating electrophysiological remodeling resulting from other cardiac diseases.

Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart

2011 ◽  
Vol 300 (2) ◽  
pp. H565-H573 ◽  
Author(s):  
Masahide Harada ◽  
Yukiomi Tsuji ◽  
Yuko S. Ishiguro ◽  
Hiroki Takanari ◽  
Yusuke Okuno ◽  
...  
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
High Frequency Stimulation ◽  
Electrophysiological Properties ◽  
Rate Dependent ◽  
Frequency Stimulation ◽  
And Control

Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF ( n = 18) and control ( n = 17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs) >1,000 ms but significantly shorter at BCLs <400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17–81%), and conduction velocity was significantly decreased in CHF (by 6–20%). In both groups, high-frequency stimulation (BCLs <150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs <150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.

Electrophysiological properties of neurons within the nucleus ambiguus of adult guinea pigs

1991 ◽  
Vol 66 (3) ◽  
pp. 744-761 ◽  
Author(s):  
S. M. Johnson ◽  
P. A. Getting
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Outward Current ◽  
Nucleus Ambiguus ◽  
Transient Outward Current ◽  
Maximum Magnitude ◽  
Action Potential Firing ◽  
Onset Of Action ◽  
Electrophysiological Properties ◽  
Single Action

1. The purpose of this study was to determine the electrophysiological properties of neurons within the region of the nucleus ambiguus (NA), an area that contains the ventral respiratory group. By the use of an in vitro brain stem slice preparation, intracellular recordings from neurons in this region (to be referred to as NA neurons, n = 235) revealed the following properties: postinhibitory rebound (PIR), delayed excitation (DE), adaptation, and posttetanic hyperpolarization (PTH). NA neurons were separated into three groups on the basis of their expression of PIR and DE: PIR cells (58%), DE cells (31%), and Non cells (10%). Non cells expressed neither PIR nor DE and no cells expressed both PIR and DE. 2. PIR was a transient depolarization that produced a single action potential or a burst of action potentials when the cell was released from hyperpolarization. In the presence of tetrodotoxin (TTX), the maximum magnitude of PIR was 7-12 mV. Under voltage-clamp conditions, hyperpolarizing voltage steps elicited a small inward current during the hyperpolarization and a small inward tail current on release from hyperpolarization. These currents, which mediate PIR, were most likely due to Q-current because they were blocked with extracellular cesium and were insensitive to barium. 3. DE was a delay in the onset of action potential firing when cells were hyperpolarized before application of depolarizing current. When cells were hyperpolarized to -90 mV for greater than or equal to 300 ms, maximum delays ranged from 150 to 450 ms. The transient outward current underlying DE was presumed to be A-current because of the current's activation and inactivation characteristics and its elimination by 4-aminopyridine (4-AP). 4. Adaptation was examined by applying depolarizing current for 2.0 s and measuring the frequency of evoked action potentials. Although there was a large degree of variability in the degree of adaptation, PIR cells tended to express less adaptation than DE and Non cells. Nearly three-fourths of all NA neurons adapted rapidly (i.e., 50% adaptation in less than 200 ms), but PIR cells tended to adapt faster than DE and Non cells. PTH after a train of action potentials was relatively rare and occurred more often in DE cells (43%) and Non cells (33%) than in PIR cells (13%). PTH had a magnitude of up to 18 mV and time constants that reflected the presence of one (1.7 +/- 1.4 s, mean +/- SD) or two components (0.28 +/- 0.13 and 4.1 +/- 2.2 s).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Functional subgroups of rat and human sensory neurons: a systematic review of electrophysiological properties

2022 ◽  
Author(s):  
Jannis Körner ◽  
Angelika Lampert
Keyword(s):  
Systematic Review ◽  
Action Potential ◽  
Sensory Neurons ◽  
Input Resistance ◽  
Immune Reactivity ◽  
Electrophysiological Properties ◽  
Electrophysiological Data ◽  
Electrophysiological Studies ◽  
Dorsal Root Ganglia Neurons ◽  
Definition Of

AbstractSensory neurons are responsible for the generation and transmission of nociceptive signals from the periphery to the central nervous system. They encompass a broadly heterogeneous population of highly specialized neurons. The understanding of the molecular choreography of individual subpopulations is essential to understand physiological and pathological pain states. Recently, it became evident that species differences limit transferability of research findings between human and rodents in pain research. Thus, it is necessary to systematically compare and categorize the electrophysiological data gained from human and rodent dorsal root ganglia neurons (DRGs). In this systematic review, we condense the available electrophysiological data defining subidentities in human and rat DRGs. A systematic search on PUBMED yielded 30 studies on rat and 3 studies on human sensory neurons. Defined outcome parameters included current clamp, voltage clamp, cell morphology, pharmacological readouts, and immune reactivity parameters. We compare evidence gathered for outcome markers to define subgroups, offer electrophysiological parameters for the definition of neuronal subtypes, and give a framework for the transferability of electrophysiological findings between species. A semiquantitative analysis revealed that for rat DRGs, there is an overarching consensus between studies that C-fiber linked sensory neurons display a lower action potential threshold, higher input resistance, a larger action potential overshoot, and a longer afterhyperpolarization duration compared to other sensory neurons. They are also more likely to display an infliction point in the falling phase of the action potential. This systematic review points out the need of more electrophysiological studies on human sensory neurons.

Basic electrophysiological properties of spinal cord motoneurons during old age in the cat

1987 ◽  
Vol 58 (1) ◽  
pp. 180-194 ◽  
Author(s):  
F. R. Morales ◽  
P. A. Boxer ◽  
S. J. Fung ◽  
M. H. Chase
Keyword(s):  
Spinal Cord ◽  
Membrane Potential ◽  
Action Potential ◽  
Old Age ◽  
Conduction Velocity ◽  
Input Resistance ◽  
Action Potential Amplitude ◽  
Electrophysiological Properties ◽  
Potential Amplitude ◽  
Versus Input

1. The electrophysiological properties of alpha-motoneurons in old cats (14–15 yr) were compared with those of adult cats (1–3 yr). These properties were measured utilizing intracellular recording and stimulating techniques. 2. Unaltered in the old cat motoneurons were the membrane potential, action potential amplitude, and slopes of the initial segment (IS) and soma dendritic (SD) spikes, as well as the duration and amplitude of the action potential's afterhyperpolarization. 3. In contrast, the following changes in the electrophysiological properties of lumbar motoneurons were found in the old cats: a decrease in axonal conduction velocity, a shortening of the IS-SD delay, an increase in input resistance, and a decrease in rheobase. 4. In spite of these considerable changes in motoneuron properties in the old cat, normal correlations between different electrophysiological properties were maintained. The following key relationships, among others, were the same in adult and old cat motoneurons: membrane potential polarization versus action potential amplitude, duration of the afterhyperpolarization versus motor axon conduction velocity, and rheobase versus input conductance. 5. A review of the existing literature reveals that neither chronic spinal cord section nor deafferentation (13, 21) in adult animals produce the changes observed in old cats. Thus we consider it unlikely that a loss of synaptic contacts was responsible for the modifications in electrophysiological properties observed in old cat motoneurons. 6. We conclude that during old age there are significant changes in the soma-dendritic portion of cat motoneurons, as indicated by the modifications found in input resistance, rheobase, and IS-SD delay, as well as significant changes in their axons, as indicated by a decrease in conduction velocity.

scholarly journals Action potential conduction between a ventricular cell model and an isolated ventricular cell

1996 ◽  
Vol 70 (1) ◽  
pp. 281-295 ◽  
Author(s):  
R. Wilders ◽  
R. Kumar ◽  
R.W. Joyner ◽  
H.J. Jongsma ◽  
E.E. Verheijck ◽  
...  
Keyword(s):  
Action Potential ◽  
Cell Model ◽  
Ventricular Cell ◽  
Ventricular Cell Model

Effects of thyroid hormone on action potential and repolarizing currents in rat ventricular myocytes

2000 ◽  
Vol 278 (2) ◽  
pp. E302-E307 ◽  
Author(s):  
Zhuo-Qian Sun ◽  
Kaie Ojamaa ◽  
William A. Coetzee ◽  
Michael Artman ◽  
Irwin Klein
Keyword(s):  
Action Potential ◽  
Cardiac Electrophysiology ◽  
Ventricular Myocytes ◽  
Outward Current ◽  
Mechanisms Of Action ◽  
Transient Outward Current ◽  
Prolonged Action ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp ◽  
Prolonged Action Potential Duration

Thyroid hormones play an important role in cardiac electrophysiology through both genomic and nongenomic mechanisms of action. The effects of triiodothyronine (T3) on the electrophysiological properties of ventricular myocytes isolated from euthyroid and hypothyroid rats were studied using whole cell patch clamp techniques. Hypothyroid ventricular myocytes showed significantly prolonged action potential duration (APD90) compared with euthyroid myocytes, APD90 of 151 ± 5 vs. 51 ± 8 ms, respectively. Treatment of hypothyroid ventricular myocytes with T3 (0.1 μM) for 5 min significantly shortened APD by 24% to 115 ± 10 ms. T3 similarly shortened APD in euthyroid ventricular myocytes, but only in the presence of 4-aminopyridine (4-AP), an inhibitor of the transient outward current ( I to), which prolonged the APD by threefold. Transient outward current ( I to) was not affected by the acute application of T3 to either euthyroid or hypothyroid myocytes; however, I to density was significantly reduced in hypothyroid compared with euthyroid ventricular myocytes.

scholarly journals Melatonin Reduces Excitability in Dorsal Root Ganglia Neurons with Inflection on the Repolarization Phase of the Action Potential

2019 ◽  
Vol 20 (11) ◽  
pp. 2611 ◽  
Author(s):  
Klausen Oliveira-Abreu ◽  
Nathalia Silva-dos-Santos ◽  
Andrelina Coelho-de-Souza ◽  
Francisco Ferreira-da-Silva ◽  
Kerly Silva-Alves ◽  
...  
Keyword(s):  
Action Potential ◽  
Dorsal Root Ganglia ◽  
Dorsal Root ◽  
Neuronal Excitability ◽  
Input Resistance ◽  
Cell Types ◽  
Neuronal Population ◽  
Resting Membrane Potential ◽  
Electrophysiological Properties ◽  
Repolarization Phase

Melatonin is a neurohormone produced and secreted at night by pineal gland. Many effects of melatonin have already been described, for example: Activation of potassium channels in the suprachiasmatic nucleus and inhibition of excitability of a sub-population of neurons of the dorsal root ganglia (DRG). The DRG is described as a structure with several neuronal populations. One classification, based on the repolarizing phase of the action potential (AP), divides DRG neurons into two types: Without (N0) and with (Ninf) inflection on the repolarization phase of the action potential. We have previously demonstrated that melatonin inhibits excitability in N0 neurons, and in the present work, we aimed to investigate the melatonin effects on the other neurons (Ninf) of the DRG neuronal population. This investigation was done using sharp microelectrode technique in the current clamp mode. Melatonin (0.01–1000.0 nM) showed inhibitory activity on neuronal excitability, which can be observed by the blockade of the AP and by the increase in rheobase. However, we observed that, while some neurons were sensitive to melatonin effect on excitability (excitability melatonin sensitive—EMS), other neurons were not sensitive to melatonin effect on excitability (excitability melatonin not sensitive—EMNS). Concerning the passive electrophysiological properties of the neurons, melatonin caused a hyperpolarization of the resting membrane potential in both cell types. Regarding the input resistance (Rin), melatonin did not change this parameter in the EMS cells, but increased its values in the EMNS cells. Melatonin also altered several AP parameters in EMS cells, the most conspicuously changed was the (dV/dt)max of AP depolarization, which is in coherence with melatonin effects on excitability. Otherwise, in EMNS cells, melatonin (0.1–1000.0 nM) induced no alteration of (dV/dt)max of AP depolarization. Thus, taking these data together, and the data of previous publication on melatonin effect on N0 neurons shows that this substance has a greater pharmacological potency on Ninf neurons. We suggest that melatonin has important physiological function related to Ninf neurons and this is likely to bear a potential relevant therapeutic use, since Ninf neurons are related to nociception.

The effects of axotomy on electrophysiological properties of B cells of bullfrog sympathetic ganglia conditioned by a previous lesion

1988 ◽  
Vol 66 (7) ◽  
pp. 942-945 ◽  
Author(s):  
M. E. M. Kelly ◽  
M. A. Bisby ◽  
K. Lukowiak
Keyword(s):  
B Cells ◽  
Action Potential ◽  
Decay Time ◽  
Sympathetic Ganglia ◽  
Membrane Properties ◽  
Electrophysiological Properties

In bullfrog sympathetic B cells, axotomy decreases the amplitude and decay time of membrane afterhyperpolarization (AHP) and increases action potential (AP) duration. A second (test) axotomy, 7 days after an initial (conditioning) axotomy, did not amplify these changes. No recovery of AHP amplitude or AP duration occurred by 56 days post-axotomy, but AHP decay time recovered 21 days earlier than after test axotomy alone. Conditioning, previously shown to accelerate regeneration, speeds the return to normal of those membrane properties previously shown to recover after axotomy.

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