A realistic model of biphasic calcium transients in electrically nonexcitable cells

A. Korngreen, V. Gol'shtein, Z. Priel

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

In many electrically nonexcitable cells, the release of calcium from internal stores is followed by a much slower phase in which the intracellular calcium concentration decreases gradually to a sustained value higher than the concentration before stimulation. This elevated calcium plateau has been shown to be the result of calcium influx. The model presented in this work describes a system consisting of a cytoplasmic calcium store and a plasma membrane calcium channel, both excitable by a membrane receptor; a fast cytoplasmic calcium buffer; and calcium pumps in both the calcium store and cellular membranes. Inherent difficulties in the numerical evaluation of the model, caused by very large calcium fluxes across the store membrane, were overcome by analytically separating the fast processes of calcium release from the slower processes of calcium cycling across the plasma membrane. This enabled the simulation of realistic biphasic calcium transients similar to those observed experimentally. The model predicted 1) a strong correlation between the rate of calcium cycling across the plasma membrane and the rate of calcium decay; and 2) a dependence on the level of cell excitation of the maximum rise in cytoplasmic calcium concentration, the level of the elevated calcium plateau, and the rate of calcium decay. Using the model, we simulated the washout of agonist from the bathing solution and the depletion of the calcium store by a pharmacological agent (such as thapsigargin) under several experimental conditions.

Original languageEnglish
Pages (from-to)659-673
Number of pages15
JournalBiophysical Journal
Volume73
Issue number2
DOIs
StatePublished - Aug 1997
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by a grant from the Israel Science Foundation. The authors would like to thank Mr. A Braiman for his comments on the manuscript.

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