Modulatory effect of NCX on IP_3-dependent Ca~(2+) oscillations in astrocytes

摘要

Most of the existing models of calcium dynamics of astrocytes do not take into account the effect of the Na/Ca-exchanger on the formation of calcium oscillations and their properties. However, recent experimental studies show that at an increased sodium concentration, the Na/Ca-exchanger works in the reverse mode, providing an additional calcium entry into the cell cytosol. In this work we study a model that simultaneously takes into account the IP_3-mediated exchange with intracellular [Ca~(2+)] stores and bidirectional [Ca~(2+)] flow through Na/Ca-exchanger. We analyze the behavior of the system under stimulation with external glutamate- of the cell, explore the possible behavior regimes and reveal the effect of the cytosolic sodium concentration, the maximum current through the Na/Ca-exchanger, and the stimulus amplitude on the astrocytic calcium dynamics.