Switching from simple to complex oscillations in calcium signaling

We present a new model for calcium oscillations based on experiments in hep atocytes. The model considers feedback inhibition on the initial agonist re ceptor complex by calcium and activated phospholipase C, as well as recepto r type-dependent self-enhanced behavior of the activated G(alpha) subunit. It is able to show simple periodic oscillations and periodic bursting, and it is the first model to display chaotic bursting in response to agonist st imulations. Moreover, our model offers a possible explanation for the diffe rences in dynamic behavior observed in response to different agonists in he patocytes.