Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"action potential duration"”.
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Augmentations vs. Restoration: A computational study of the effects of bacterial sodium channels on cardiac conduction.
… channels, or BacNavs, have shown promise for potentially alleviating these arrhythmias. However, due to size constraints, only the BacNavs are available for the highest efficiency viral vectors for stable transduction. Limitations in the ability to test these channels in adult mammalian …
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Computational Studies of the Concealed Gating Pathways and Electrophysiological Function of the Human Cardiac IKs Channel
… (by PIP2) of IKs and its role in cardiac action potential duration shortening during beta-adrenergic stimulation was also studied. Channel subconductances are shown to depend on the pore energy profile and entire protein structure. The Machine Learning approach is applicable to …
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Investigating the coordination of cardiac conduction and repolarization in ventricular myocardium
… increases the risk of arrhythmia. Calcium may potentially play a role in modulating APD adaptation to pacing rate in the context of this disease state, though more research is needed to clarify the exact mechanism of this effect. Finally, we investigate the relationship between conduction and …
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Atrial arrhythmogenesis in a murine model of mitochondrial insufficiency
… Sharp microelectrode recordings of cellular action potentials (AP) in a whole-heart Langendorff-perfused system revealed that the Pgc-1β-/- genotype was associated with an atrial arrhythmic phenotype that progressed with age. Young and aged Pgc-1β-/- hearts showed evidence of slowed AP …
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Human Nav1.5 F1486 deletion associated with long-QT syndrome leads to deficiency in inactivation and reduces lidocaine sensitivity
… the initiation and propagation of the cardiac action potentials. Mutations of SCN5A, the gene that encodes Nav1.5, have been well documented to cause long-QT syndrome (LQTs) by disrupting channel inactivation and increasing late sodium current. Previous studies have revealed the importance of …
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Spatial Variation of Cardiac Restitution and the Onset of Alternans
… is used to determine the spatial dependence of action potential duration (APD) and the slope of the dynamic restitution curve S<sub>DRC</sub>, which describes the relationship between steady-state APD and diastolic interval. For tissue with nearly identical cells, I find that APD is longest near …
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Arrhythmogenic mechanisms of acute cardiac infection
… of isolated cardiomyocytes revealed prolonged action potential duration, along with decreased potassium current density during infection. Pairing mouse work with human induced pluripotent stem cell-derived cardiomyocytes, we found that human adenovirus type-5 infection increased pCx43-Ser368 …
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Metabifurcation analysis of a phenomenological ventricular cell model
… plots, which show the model re- sponses, like action potential duration(APD) restitution curves, to a sequential change in pacing frequency. According to the bifurcation patterns, we partition the parameter space in _ve \parent families". After investigating and characterizing them in depth, we …
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The role of the perinexus in Long QT Syndrome Type 3
Gain of function of cardiac voltage-gated sodium channel (Nav1.5) leads to Long QT Syndrome Type 3 (LQT3). LQT3 phenotype can be exacerbated by expanding the perinexus, which is an intercellular nanodomain with high density of Nav1.5 in the intercalated disc. Following this finding, we found that …
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Arrhythmogenic potential of alpha-adrenoceptor stimulation in the rat heart
… being an indirect index of prolongation of the action potential duration. The arrhythmogenic action of methoxamine was associated with a positive inotropic effect. Prazosin 10⁻⁸M (an alpha₁-adrenoceptor antagonist agent) produced a tenfold displacement to the right of the log concentration …
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Postsynaptic Cholinergic Control Of Cardiac Function In Aging
… hyperpolarization of the resting membrane potential in atria but not ventricles and (b) more pronounced carbachol-induced shortening of the action potential duration measured at 50% of repolarization in the ventricles but not in the atria. (v) Aging did not alter the carbachol-induced …
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Arrhythmia mechanisms in acute ischaemia and chronic infarction in rabbit heart
… the voltage sensitive dye RH237 and optical action potentials were recorded from a 13x13mm area of left ventricular epicardium using a 16x16 element Hamamatsu photodiode array. Contraction motion artefacts were practically eliminated with blebbistatin (5µM). An alternative mechanical …
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The electrophysiological effects of Endothelin-1 in human atrial myocytes
… L-type calcium current (ICaL) and consequently action potentials. Hypotheses: ET-1 modulates the effects of isoproterenol (ISO) on ICaL and action potentials in human atrial myocytes. Methods: Atrial myocytes were isolated enzymatically from samples of right atrial appendage obtained from …
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The electrophysiological and molecular effects of chronic beta-adrenoceptor antagonist therapy on human atrium
… associated with prolongation of the atrial cell action potential duration (APD), potentially contributing to the ability of these drugs to prevent atrial fibrillation (AF). The mechanisms underlying this APD prolongation are not fully understood but may involve pharmacological remodelling of …
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Uncertainty in the Bifurcation Diagram of a Model of Heart Rhythm Dynamics
… of a two-dimensional return-map model of cardiac action potential duration (APD) restitution in a paced single cell. Uncertainty was considered in four parameters of the model: three time constants and the pacing stimulus strength. The basic cycle length (BCL) (the period between stimuli) was …
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The Role of the TBX5-driven Regulatory Network in the Manifestation and Sustainability of Atrial Fibrillation
… and downregulated IK1 to be the main cause of action potential duration (APD) prolongation, and impaired TBX5-induced EADs and DADs/SDs due to an elevation of intracellular Ca2+ ([Ca2+]i). However, the latter channel also caused unphysiological depolarization of the resting membrane potential …
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Development, Validation, and Application of Electromyometrial Imaging (EMMI) to Noninvasively Image Uterine Contractions
<p>Clinically, uterine contraction and labor progression are monitored via tocodynamometers (TOCO) or intrauterine pressure catheters (IUPC). However, these clinical tools measure the crude pressure information and have limit specificity and accuracy in differentiating the contractions, whether …