TRANSITIONS OF LATENCY TIME AND OSCILLATION PHASE ON PARAMETER SURFACES FROM MODELS OF INTRACELLULAR CALCIUM-ION DYNAMICS

The dynamics of two classical elementary compartmental models simulati ng intracellular calcium ion oscillatory behavior are examined in term s of parameter surfaces. It has been found that, along certain lines o f instability on surfaces defined by model parameters, the highly non- linear nature of these models produces sharp transitions in the latenc y time which determines the phase of oscillations once they commence. This sensitivity to initial conditions in deterministic models, along with the stochastic variance inevitably present in actual biological s ystems, illustrates how two seemingly identical cells activated by ide ntical synchronous stimulation can exhibit oscillatory responses which are out of phase with respect to each other.