Oscillatory activity in cells: multi-stability and hysteresis

Oscillatory activity of cells has been the topic of many studies. Oscillatory activity can be due to action potential firing corresponding to the well-known Hodgkin-Huxley (HH) type dynamics of ion-channels in the cell membrane or due to IP3-mediated calcium oscillations in the endoplasmic reticulum (ER) causing periodic oscillations of calcium transients in the cytosol. In this study we show that coupling of these two oscillatory mechanisms may reveal a complex, rich spectrum of both stable and unstable states of cells with hysteresis. The predicted bi-stability corresponds to experimentally observed states. This illustrates that the different behavior of cells is not the consequence of differentiation in cells with different properties, but rather reflects different states of a single cell type.