(V.B. Kazantsev, A.V. Semyanov, A.V. Vorobiev, S.Yu. Asatryan, A. Varentsova) We investigate dynamic processes of spontaneous and stimulus-induced calcium signal generation in astrocytes. On the base of the kinetic model describing intracellular calcium concentration in astrocytes (De Young & Keiser, 1992, Li & Rinzel, 1994, Ullah et al., 2006) we study dynamical mechanisms of calcium pulse generation and the dynamics of cell response on extracellular chemical stimulation, e.g. glutamate injection. Similar to neuronal networks, the astrocytes form networks due to gap junctions. The gap junctions are permeable to inositol 1,4,5-triphosphate (IP3) diffusing between neighboring astrocytes. In particular, such interaction can lead to spontaneous generation of quasisinusoidal subthreshold oscillations of free intracellular calcium in the range of 0.11-0.12 Hz. The presence of such oscillations may facilitate calcium pulse generation by lowering effective excitation threshold. It can be one of mechanisms for formation of calcium activity patterns.

Schematic of astrocytes interacting via gap junctions

Fig. 1. Schematic of astrocytes interacting via gap junctions.

Calcium activity pattern

Fig. 2. Calcium activity pattern in the network of astrocytes and corresponding power spectrum of mean field oscillations.