@article{O'Ne_2004_121, abstract = {Waves of calcium-induced calcium release occur in a variety of cell types and have been implicated in the origin of cardiac arrhythmias. We have investigated the effects of inhibiting the SR {C}a$^{2+}$-ATPase (SERCA) with the reversible inhibitor 2',5'-di(tert-butyl)-1,4-benzohydroquinone (TBQ) on the properties of these waves. Cardiac myocytes were voltage clamped at a constant potential between -65 and -40 mV and spontaneous waves evoked by increasing external {C}a$^{2+}$ concentration to 4 mm. Application of 100 microm TBQ decreased the frequency of waves. This was associated with increases of resting [{C}a$^{2+}$](i), the time constant of decay of [{C}a$^{2+}$](i) and the integral of the accompanying {N}a$^{+}$-{C}a$^{2+}$ exchange current. There was also a decrease in propagation velocity of the waves. There was an increase of the calculated {C}a$^{2+}$ efflux per wave. The SR {C}a$^{2+}$ content when a wave was about to propagate decreased to 91.7 +/- 3.2\%. The period between waves increased in direct proportion to the {C}a$^{2+}$ efflux per wave meaning that TBQ had no effect on the {C}a$^{2+}$ efflux per unit time. We conclude that (i) decreased wave frequency is not a direct consequence of decreased {C}a$^{2+}$ pumping by SERCA between waves but, rather, to more {C}a$^{2+}$ loss on each wave; (ii) inhibiting SERCA increases the chance of spontaneous {C}a$^{2+}$ release propagating at a given SR content.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {O'Neill, S. C. and Miller, L. and Hinch, R. and Eisner, D. A.}, biburl = {https://www.bibsonomy.org/bibtex/2b2b4d86bc9ea4aa242432119521141dc/hake}, description = {The whole bibliography file I use.}, doi = {10.1113/jphysiol.2003.058917}, file = {O'Ne_2004_121.pdf:O'Ne_2004_121.pdf:PDF}, interhash = {d52048282bec9dca2d4a37833a6e6957}, intrahash = {b2b4d86bc9ea4aa242432119521141dc}, journal = {J. Physiol.}, key = 270, keywords = {15194743 ATPase, Action Algorithms, Animals, Calcium Calcium, Cardiac, Cardiovascular, Cell Cells, Channel Channel, Channels, Comparative Computer Computing, Conduction, Conductivity, Contraction, Cultured, Electric Electrophysiology, Enzyme Gating, Gov't, Heart Heart, Humans, Inhibitors, Ion L-Type, Magnetics, Mathematical Membrane Membrane, Models, Muscle Myocardial Myocytes, Neural Neurological, Neurons, Non-U.S. P.H.S., Potentials, Rate, Rats, Receptor Release Research Reticulum, Ryanodine Sarcolemma, Sarcoplasmic Signaling, Simulation, Sodium Study, Support, Synaptic Transmission, U.S. Ventricles, {C}a$^{2+}$-Transporting}, month = Aug, number = {Pt 1}, pages = {121--128}, pii = {jphysiol.2003.058917}, pmid = {15194743}, timestamp = {2009-06-03T11:21:24.000+0200}, title = {Interplay between SERCA and sarcolemmal {C}a$^{2+}$ efflux pathways controls spontaneous release of {C}a$^{2+}$ from the sarcoplasmic reticulum in rat ventricular myocytes.}, url = {http://dx.doi.org/10.1113/jphysiol.2003.058917}, volume = 559, year = 2004 } @article{Hinc_2004_1887, abstract = {Cardiac waves can fail to propagate when the membrane potential of the cells in the wavefront rises too slowly. The sodium channel inactivation gates play an important role in this process of propagation block. Simple models including inactivation gates can have travelling waves of constant form with two possible velocities. A stability analysis demonstrates that the slower velocity is always unstable, and in limited parameter regimes the faster velocity can also be unstable. Waves with the lower velocity propagate a finite distance before they dissipate due to this instability and this distance is calculated. The distance can be large suggesting that they might be seen in certain pathological conditions. The analytical results are compared with numerical simulations of the simplified model and a detailed cardiac ionic model.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Hinch, R.}, biburl = {https://www.bibsonomy.org/bibtex/2d189bef70e7759fb8244abad353bf48e/hake}, description = {The whole bibliography file I use.}, doi = {10.1016/j.bulm.2004.05.004}, file = {Hinc_2004_1887.pdf:Hinc_2004_1887.pdf:PDF}, interhash = {16cc2373c8097aa826a9ba6f6a2609b8}, intrahash = {d189bef70e7759fb8244abad353bf48e}, journal = {Bull. Math. Biol.}, keywords = {15522359 Action Animals, Cardiovascular, Cells, Channels, Computing, Conduction, Electrophysiology, Gov't, Heart Heart, Humans, Magnetics, Mathematical Models, Muscle Neural Neurological, Neurons, Non-U.S. Potentials, Rate, Research Sodium Support,}, month = Nov, number = 6, pages = {1887--1908}, pii = {S0092824004000503}, pmid = {15522359}, timestamp = {2009-06-03T11:21:14.000+0200}, title = {Stability of cardiac waves.}, url = {http://dx.doi.org/10.1016/j.bulm.2004.05.004}, volume = 66, year = 2004 } @article{Hinc_2004_1293, abstract = {Calcium sparks are local regenerative releases of {C}a$^{2+}$ from a cluster of ryanodine receptors on the sarcoplasmic reticulum. During excitation-contraction coupling in cardiac cells, {C}a$^{2+}$ sparks are triggered by {C}a$^{2+}$ entering the cell via the T-tubules ({C}a$^{2+}$-induced {C}a$^{2+}$ release). However under conditions of calcium overload, {C}a$^{2+}$ sparks can be triggered spontaneously. The exact process by which {C}a$^{2+}$ sparks terminate is still an open question, although both deterministic and stochastic processes are likely to be important. In this article, asymptotic methods are used to analyze a single {C}a$^{2+}$ spark model, which includes both deterministic and stochastic biophysical mechanisms. The analysis calculates both spark frequencies and spark duration distributions, and shows under what circumstances stochastic transitions are important. Additionally, a model of the coupling of the release channels via the FK-binding protein is analyzed.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Hinch, R.}, biburl = {https://www.bibsonomy.org/bibtex/22750effa77dd0f3a146aaaa903f59f13/hake}, description = {The whole bibliography file I use.}, file = {Hinc_2004_1293.pdf:Hinc_2004_1293.pdf:PDF}, interhash = {62dbb8bc8e42a30e7fabfa270b5ce7d0}, intrahash = {2750effa77dd0f3a146aaaa903f59f13}, journal = {Biophys. J.}, key = 62, keywords = {14990462 ATPase, Action Animals, Biological, Calcium Calcium, Cardiac, Cardiovascular, Cell Cells, Channel Channel, Channels, Comparative Computer Computing, Conduction, Contraction, Cultured, Electrophysiology, Enzyme Gating, Gov't, Heart Heart, Humans, Inhibitors, Ion L-Type, Magnetics, Mathematical Membrane Membrane, Models, Muscle Myocardial Myocytes, Neural Neurological, Neurons, Non-U.S. P.H.S., Potentials, Processes, Rate, Rats, Receptor Release Research Reticulum, Ryanodine Sarcolemma, Sarcoplasmic Signaling, Simulation, Sodium Statistical, Stochastic Study, Support, U.S. Ventricles, {C}a$^{2+}$-Transporting}, month = Mar, number = 3, pages = {1293--1307}, pmid = {14990462}, timestamp = {2009-06-03T11:21:14.000+0200}, title = {A mathematical analysis of the generation and termination of calcium sparks.}, url = {http://www.biophysj.org/cgi/content/full/86/3/1293}, volume = 86, year = 2004 } @article{Elf_2004_230, abstract = {Bi-stable chemical systems are the basic building blocks for intracellular memory and cell fate decision circuits. These circuits are built from molecules, which are present at low copy numbers and are slowly diffusing in complex intracellular geometries. The stochastic reaction-diffusion kinetics of a double-negative feedback system and a MAPK phosphorylation-dephosphorylation system is analysed with Monte-Carlo simulations of the reaction-diffusion master equation. The results show the geometry of intracellular reaction compartments to be important both for the duration and the locality of biochemical memory. Rules for when the systems lose global hysteresis by spontaneous separation into spatial domains in opposite phases are formulated in terms of geometrical constraints, diffusion rates and attractor escape times. The analysis is facilitated by a new efficient algorithm for exact sampling of the Markov process corresponding to the reaction-diffusion master equation.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Elf, J. and Ehrenberg, M.}, biburl = {https://www.bibsonomy.org/bibtex/28cafd3865762af7232067148d31528db/hake}, description = {The whole bibliography file I use.}, doi = {10.1049/sb:20045021}, file = {Elf_2004_230.pdf:Elf_2004_230.pdf:PDF}, interhash = {edcbf874ae1b483a663784af57559b14}, intrahash = {8cafd3865762af7232067148d31528db}, issn = {1741-2471}, journal = {Systems Biology, IEE Proceedings}, keywords = {Carlo MAPK Markov Monte attractor bi-stable biochemical biochemistry, biodiffusion, biology biophysics, cell cellular circuits, computing, decision diffusion, domains, double-negative equation, escape fate feedback feedback, intracellular kinetics master memory, methods, molecular opposite phases, phosphorylation-dephosphorylation process, processes, reaction-diffusion separation, simulations, spatial spontaneous stochastic system, systems systems, times,}, number = 2, pages = {230--236}, timestamp = {2009-06-03T11:21:10.000+0200}, title = {Spontaneous separation of bi-stable biochemical systems into spatial domains of opposite phases}, url = {http://dx.doi.org/10.1049/sb:20045021}, volume = 1, year = 2004 } @article{Coom_2004_197, abstract = {Calcium ions are an important second messenger in living cells. Indeed calcium signals in the form of waves have been the subject of much recent experimental interest. It is now well established that these waves are composed of elementary stochastic release events (calcium puffs or sparks) from spatially localised calcium stores. The aim of this paper is to analyse how the stochastic nature of individual receptors within these stores combines to create stochastic behaviour on long time-scales that may ultimately lead to waves of activity in a spatially extended cell model. Techniques from asymptotic analysis and stochastic phase-plane analysis are used to show that a large cluster of receptor channels leads to a release probability with a sigmoidal dependence on calcium density. This release probability is incorporated into a computationally inexpensive model of calcium release based upon a stochastic generalisation of the fire-diffuse-fire ({FDF}) threshold model. Numerical simulations of the model in one and two dimensions (with stores arranged on both regular and disordered lattices) illustrate that stochastic calcium release leads to the spontaneous production of calcium sparks that may merge to form saltatory waves. Illustrations of spreading circular waves, spirals and more irregular waves are presented. Furthermore, receptor noise is shown to generate a form of array enhanced coherence resonance whereby all calcium stores release periodically and simultaneously.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Coombes, S. and Hinch, R. and Timofeeva, Y.}, biburl = {https://www.bibsonomy.org/bibtex/2b85ddc6de57b121870d67927cd03682c/hake}, description = {The whole bibliography file I use.}, doi = {10.1016/j.pbiomolbio.2004.01.015}, file = {Coom_2004_197.pdf:Coom_2004_197.pdf:PDF}, interhash = {13f1d295c83d5beb4e8656c63a92cc99}, intrahash = {b85ddc6de57b121870d67927cd03682c}, journal = {Prog. Biophys. Mol. Biol.}, key = 131, keywords = {15142744 ATPase, Action Animals, Biological, Calcium Calcium, Cardiac, Cardiovascular, Cell Cells, Channel Channel, Channels, Comparative Computer Computing, Conduction, Contraction, Cultured, Electrophysiology, Enzyme Gating, Gov't, Heart Heart, Humans, Inhibitors, Ion L-Type, Magnetics, Mathematical Membrane Membrane, Models, Muscle Myocardial Myocytes, Neural Neurological, Neurons, Non-U.S. P.H.S., Potentials, Processes, Rate, Rats, Receptor Release Research Reticulum, Ryanodine Sarcolemma, Sarcoplasmic Signaling, Simulation, Sodium Statistical, Stochastic Study, Support, U.S. Ventricles, {C}a$^{2+}$-Transporting}, number = {2-3}, pages = {197--216}, pii = {S0079610704000276}, pmid = {15142744}, timestamp = {2009-06-03T11:21:09.000+0200}, title = {Receptors, sparks and waves in a fire-diffuse-fire framework for calcium release.}, url = {http://dx.doi.org/10.1016/j.pbiomolbio.2004.01.015}, volume = 85, year = 2004 }