Simulation of Spontaneous Ca Oscillations in Astrocytes Mediated by Voltage-Gated Calcium Channels

The purpose of this computational study was to investigate the possible role of voltage-gated Ca²⁺ channels in spontaneous Ca²⁺ oscillations of astrocytes. By incorporating different types of voltage-gated Ca²⁺ channels and a previous model, this study reproduced typical Ca²⁺ oscillations in silico. Our model could mimic the oscillatory phenomenon under a wide range of experimental conditions, including resting membrane potential (−75 to −60 mV), extracellular Ca²⁺ concentration (0.1 to 1500 μM), temperature (20 to 37°C), and blocking specific Ca²⁺ channels. By varying the experimental conditions, the amplitude and duration of Ca²⁺ oscillations changed slightly (both <25%), while the frequency changed significantly (∼400%). This indicates that spontaneous Ca²⁺ oscillations in astrocytes might be an all-or-none process, which might be frequency-encoded in signaling. Moreover, the properties of Ca²⁺ oscillations were found to be related to the dynamics of Ca²⁺ influx, and not only to a constant influx. Therefore, calcium channels dynamics should be used in studying Ca²⁺ oscillations. This work provides a platform to explore the still unclear mechanism of spontaneous Ca²⁺ oscillations in astrocytes.