Simulation of Spontaneous Ca2+ 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 MM), temperature (20 to 37 degrees 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 (similar to 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.