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arXiv · 2401.16839

Understanding broad-spike oscillations in a model of intracellular calcium dynamics

Behnaz Rahmani·Samuel Jelbart·Vivien Kirk·James Sneyd
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Abstract

Oscillations of free intracellular calcium concentration are thought to be important in the control of a wide variety of physiological phenomena, and there is long-standing interest in understanding these oscillations via the investigation of suitable mathematical models. Many of these models have the feature that different variables or terms in the model evolve on very different time-scales, which often results in the accompanying oscillations being temporally complex. Cloete et al [5] constructed an ordinary differential equation model of calcium oscillations in hepatocytes in an attempt to understand the origin of two distinct types of oscillation observed in experiments: narrow-spike oscillations in which rapid spikes of calcium concentration alternate with relatively long periods of quiescence, and broad-spike oscillations in which there is a fast rise in calcium levels followed by a slower decline then a period of quiescence. These two types of oscillation can be observed in the model if a single system parameter is varied but the mathematical mechanisms underlying the different types of oscillations were not explored in detail in [5]. We use ideas from geometric singular perturbation theory to investigate the origin of broad-spike solutions in this model. We find that the analysis is intractable in the full model, but are able to uncover structure in particular singular limits of a related model that point to the origin of the broad-spike solutions.

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Behnaz Rahmani, Samuel Jelbart, Vivien Kirk, James Sneyd. 2024-01-30. Understanding broad-spike oscillations in a model of intracellular calcium dynamics. https://arxiv.org/abs/2401.16839

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