Equations for InsP3 receptor-mediated [Ca2+](i) oscillations derived from a detailed kinetic model: A Hodgkin-Huxley like formalism

Y. X. Li, J. Rinzel

Research output: Contribution to journalArticle

Abstract

The nine-variable De Young-Keizer model (1992) for [Ca2+](i) oscillations mediated by InsP3 receptor channels in endoplasmic reticulum (ER) membrane is analyzed and reduced to a two-variable system. The different time scales in the three basic channel gating processes, namely InsP3 regulation, Ca2+ activation, and Ca2+ inactivation, are revealed and characterized. The method of multiple scales is used in solving the equations on a succession of faster time scales and reducing them to a 2D system. The reduced system, (V(cy)/f(cy)) dC/dt = - P(IP3R)m(∞)/3h3(C - C0) - P(L)(C - C0) - J(pump)(C); dh/dt = (h(∞) - h)/τ(h), is analogous in form to the Hodgkin-Huxley equations for plasma membrane electrical excitability. [Ca2+](i) dynamics in this model thus involve ER membrane-associated excitability. The reduced system has a bifurcation diagram almost identical to that of the original system and retains the most important dynamic features of the latter. The analysis also shows that the reduced system becomes simpler when the different gating processes are more independent from each other, i.e. when the rates for Ca2+ binding at the site associated with one gating process are independent of occupancy at the other two binding sites. Assuming further that binding of InsP3 does not depend on Ca2+ occupancy at the inactivation site, we obtain a 'minimal' form yet retain significant ability to reproduce experimental observations.

Original languageEnglish (US)
Pages (from-to)461-473
Number of pages13
JournalJournal of Theoretical Biology
Volume166
Issue number4
DOIs
StatePublished - 1994

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Kinetic Model
Endoplasmic Reticulum
Receptor
oscillation
Binding Sites
Oscillation
Membranes
calcium
kinetics
receptors
Kinetics
Binding sites
Cell membranes
Excitability
Chemical activation
Cell Membrane
Pumps
endoplasmic reticulum
inactivation
Time Scales

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

Cite this

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title = "Equations for InsP3 receptor-mediated [Ca2+](i) oscillations derived from a detailed kinetic model: A Hodgkin-Huxley like formalism",
abstract = "The nine-variable De Young-Keizer model (1992) for [Ca2+](i) oscillations mediated by InsP3 receptor channels in endoplasmic reticulum (ER) membrane is analyzed and reduced to a two-variable system. The different time scales in the three basic channel gating processes, namely InsP3 regulation, Ca2+ activation, and Ca2+ inactivation, are revealed and characterized. The method of multiple scales is used in solving the equations on a succession of faster time scales and reducing them to a 2D system. The reduced system, (V(cy)/f(cy)) dC/dt = - P(IP3R)m(∞)/3h3(C - C0) - P(L)(C - C0) - J(pump)(C); dh/dt = (h(∞) - h)/τ(h), is analogous in form to the Hodgkin-Huxley equations for plasma membrane electrical excitability. [Ca2+](i) dynamics in this model thus involve ER membrane-associated excitability. The reduced system has a bifurcation diagram almost identical to that of the original system and retains the most important dynamic features of the latter. The analysis also shows that the reduced system becomes simpler when the different gating processes are more independent from each other, i.e. when the rates for Ca2+ binding at the site associated with one gating process are independent of occupancy at the other two binding sites. Assuming further that binding of InsP3 does not depend on Ca2+ occupancy at the inactivation site, we obtain a 'minimal' form yet retain significant ability to reproduce experimental observations.",
author = "Li, {Y. X.} and J. Rinzel",
year = "1994",
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journal = "Journal of Theoretical Biology",
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T1 - Equations for InsP3 receptor-mediated [Ca2+](i) oscillations derived from a detailed kinetic model

T2 - A Hodgkin-Huxley like formalism

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AU - Rinzel, J.

PY - 1994

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N2 - The nine-variable De Young-Keizer model (1992) for [Ca2+](i) oscillations mediated by InsP3 receptor channels in endoplasmic reticulum (ER) membrane is analyzed and reduced to a two-variable system. The different time scales in the three basic channel gating processes, namely InsP3 regulation, Ca2+ activation, and Ca2+ inactivation, are revealed and characterized. The method of multiple scales is used in solving the equations on a succession of faster time scales and reducing them to a 2D system. The reduced system, (V(cy)/f(cy)) dC/dt = - P(IP3R)m(∞)/3h3(C - C0) - P(L)(C - C0) - J(pump)(C); dh/dt = (h(∞) - h)/τ(h), is analogous in form to the Hodgkin-Huxley equations for plasma membrane electrical excitability. [Ca2+](i) dynamics in this model thus involve ER membrane-associated excitability. The reduced system has a bifurcation diagram almost identical to that of the original system and retains the most important dynamic features of the latter. The analysis also shows that the reduced system becomes simpler when the different gating processes are more independent from each other, i.e. when the rates for Ca2+ binding at the site associated with one gating process are independent of occupancy at the other two binding sites. Assuming further that binding of InsP3 does not depend on Ca2+ occupancy at the inactivation site, we obtain a 'minimal' form yet retain significant ability to reproduce experimental observations.

AB - The nine-variable De Young-Keizer model (1992) for [Ca2+](i) oscillations mediated by InsP3 receptor channels in endoplasmic reticulum (ER) membrane is analyzed and reduced to a two-variable system. The different time scales in the three basic channel gating processes, namely InsP3 regulation, Ca2+ activation, and Ca2+ inactivation, are revealed and characterized. The method of multiple scales is used in solving the equations on a succession of faster time scales and reducing them to a 2D system. The reduced system, (V(cy)/f(cy)) dC/dt = - P(IP3R)m(∞)/3h3(C - C0) - P(L)(C - C0) - J(pump)(C); dh/dt = (h(∞) - h)/τ(h), is analogous in form to the Hodgkin-Huxley equations for plasma membrane electrical excitability. [Ca2+](i) dynamics in this model thus involve ER membrane-associated excitability. The reduced system has a bifurcation diagram almost identical to that of the original system and retains the most important dynamic features of the latter. The analysis also shows that the reduced system becomes simpler when the different gating processes are more independent from each other, i.e. when the rates for Ca2+ binding at the site associated with one gating process are independent of occupancy at the other two binding sites. Assuming further that binding of InsP3 does not depend on Ca2+ occupancy at the inactivation site, we obtain a 'minimal' form yet retain significant ability to reproduce experimental observations.

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