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The Global ETD Search service is a free service for researchers
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Showing 1 to 6 of 6 (0.02 seconds)Spelling suggestions: "subject:"ttubule"" "subject:"tubule""
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Modelling the spatio-temporal dynamic of iIntracellular Ca2+ handling system in cardiac cellsHe, Yang January 2017 (has links)
The intracellular Ca2+ handling system in a cardiac myocyte is of crucial importance. It regulates the contraction and relaxation of the myocyte during the excitation-contraction (EC) coupling. A normal intracellular Ca2+ handling system keeps the contraction of the heart orderly, which represents a powerful force to pump blood to the whole body. However, disarrayed or remodelled cellular structure associated with the intracellular Ca2+ handling system at the subcellular level, such as loss of T-tubule network in diseased conditions, may promote abnormal cardiac EC coupling, leading to genesis of cardiac arrhythmias impairing cardiac mechanical functions. Up to date, it is still incompletely understood how the intracellular Ca2+ handling system is altered by changes in subcellular structures of Ca2+ handling systems. In this thesis, biophysically detailed computational models for the intracellular Ca2+ handling system of a cardiac cell were developed, providing a powerful platform to investigate the spatio-temporal complexity associated with the intracellular Ca2+ handling, and its role in generating abnormal cardiac EC coupling. First, a well-validated single cell model was used to investigate how the diastolic and systolic Ca2+ concentration responded to alterations in the model parameters related to the Ca2+ handling system, from which the mechanisms underlying the rate-dependence of EC coupling were analysed. Then, a novel single cell model, with a 2D presentation of the spatial structures of subcellular Ca2+ handling and membrane action potential, of a sheep atrial myocyte was developed for simulating the abnormal intracellular Ca2+ regulation system due to the loss of T-tubules during atrial fibrillation. Variant scenarios of T-tubule loss were considered to investigate the role of the T-tubule in affecting the intracellular Ca2+ regulation. Furthermore, membrane currents' alterations due to the electrical remodelling arising from atrial fibrillation were considered together with the loss of T-tubule. Three typical types of abnormal Ca2+ cycling phenomenon, namely intracellular Ca2+ alternans, spontaneous Ca2+ sparks and intracellular Ca2+ waves were observed in AF conditions. The relationship between T-tubule loss, AF-remodelling and the genesis of delayed afterdepolarizations (DADs) was also investigated. It was shown that the loss of T-tubule in AF condition played an important role in disturbing the Ca2+ regulation system, which increases the risk for a cell to generate impaired contraction.
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Cardiac T-Tubule Membranes - Nanostructure and Remodeling Mechanisms in DiseaseWagner, Eva 10 December 2012 (has links)
No description available.
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Modulation Of Cardiac Inward-Rectifier K+ Current IK1 By Intracellular K+ And Extracellular K+Dyachok, Oksana 13 December 2011 (has links)
The inwardly-rectifying K+ current (IK1) is important for heart cell function because it sets the resting potential, influences cell excitability, and promotes repolarization of the action potential. My objective was to investigate the modulation of IK1 by extracellular K+ (K+o) and intracellular K+ (K+i). IK1 was recorded from whole-cell-configured guinea-pig ventricular myocytes that were dialyzed with Na+-free EGTA-buffered pipette-filling solution and bathed with Na+ or NMDG+ solution that contained agents that inhibit non-IK1 currents.
Lowering K+o from standard 5.4 to 2 and 1 mM shifted the reversal potential (Erev) of IK1 in accord with calculated K+ equilibrium potential (EK), and altered IK1 amplitude in accord with conductance (GK1)? ?K+o. Surprisingly, myocytes bathed with 0-mM K+ solution had a small outward IK1 at holding potential (Vhold) ?85 mV. This IK1 was attributed to channel-activation by T-tubular K+ (K+T) whose concentration is sensitive to the flow of T-tubular IK1. K+T in myocytes bathed with 0-mM K+ solution was ? 3.2 mM at Vhold ?85 mV, but ? 0.3 mM following large K+T-depleting flows of inward IK1 at ?160 mV. Results consistent with interplay of IK1 and K+T were also obtained in experiments on myocytes bathed with 2-, 5.4-, and 15-mM K+ solution.
Myocytes were dialyzed with pipette solutions that contained 0-140 mM K+ to investigate modulation by K+i. When IK1 at Vhold was kept small, Erev varied with pipette K+ in a near-Nernstian manner (i.e., Erev ? EK); however, when IK1 (Vhold) was large and inward, Erev was markedly negative to nominal EK. Findings in experiments that involved shifting Vhold, changing K+o, and application of Ba2+ and Cs+ suggest that the magnitude/direction of IK1 strongly affects the concentration of K+ in submembrane cytoplasm. Classical GK1-voltage parameters GK1max and V0.5 (but not slope factor) were affected by decreases in K+i: GK1max declined by ? 25% per decade decrease in K+i, and V0.5 shifted approximately as 0.5 ? EK-shift. The latter findings are discussed and compared with those of earlier studies on the dependence of inwardly-rectifying K+ conductance on K+i.
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Modeling of excitation in skeletal muscleMetzger, Sabrina Kinzie 14 May 2021 (has links)
No description available.
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Multi-facet Roles of MG29, a Synaptophysin Family Protein, in Skeletal Muscle Development, Regeneration, and Metabolic FunctionYi, Frank January 2021 (has links)
No description available.
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Über die differentielle Regulation von Ionenkanälen in spezifischen Nanodomänen atrialer und ventrikulärer Kardiomyozyten / Differential Regulation of Ion Channels in Specific Nanodomains of Atrial and Ventricular CardiomyocytesBrandenburg, Sören 29 June 2017 (has links)
No description available.
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