Simplification and analysis of models of calcium dynamics based on IP3-sensitive calcium channel kinetics
Autor: | John L. Stephenson, Yuanhua Tang, Hans G. Othmer |
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Rok vydání: | 1996 |
Předmět: |
Intracellular Fluid
Male Differential equation Xenopus Kinetics Biophysics chemistry.chemical_element Receptors Cytoplasmic and Nuclear Inositol 1 4 5-Trisphosphate Calcium In Vitro Techniques Models Biological Calcium in biology Biophysical Phenomena 03 medical and health sciences 0302 clinical medicine Animals Inositol 1 4 5-Trisphosphate Receptors 030304 developmental biology 0303 health sciences Ion Transport Calcium channel Function (mathematics) Biochemistry chemistry Oocytes Female Calcium Channels Extracellular Space 030217 neurology & neurosurgery Intracellular Mathematics Communication channel Research Article |
Zdroj: | Biophysical journal. 70(1) |
ISSN: | 0006-3495 |
Popis: | We study the models for calcium (Ca) dynamics developed in earlier studies, in each of which the key component is the kinetics of intracellular inositol-1,4,5-trisphosphate-sensitive Ca channels. After rapidly equilibrating steps are eliminated, the channel kinetics in these models are represented by a single differential equation that is linear in the state of the channel. In the reduced kinetic model, the graph of the steady-state fraction of conducting channels as a function of log10(Ca) is a bell-shaped curve. Dynamically, a step increase in inositol-1,4,5-trisphosphate induces an incremental increase in the fraction of conducting channels, whereas a step increase in Ca can either potentiate or inhibit channel activation, depending on the Ca level before and after the increase. The relationships among these models are discussed, and experimental tests to distinguish between them are given. Under certain conditions the models for intracellular calcium dynamics are reduced to the singular perturbed form epsilon dx/d tau = f(x, y, p), dy/d tau = g(x, y, p). Phase-plane analysis is applied to a generic form of these simplified models to show how different types of Ca response, such as excitability, oscillations, and a sustained elevation of Ca, can arise. The generic model can also be used to study frequency encoding of hormonal stimuli, to determine the conditions for stable traveling Ca waves, and to understand the effect of channel properties on the wave speed. |
Databáze: | OpenAIRE |
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