Fig. 6.

Slow [Na⁺]_c changes as a pacemaker. Typical computer simulations using the model by Fridlyand et al. (51). Slow bursting and the oscillation patterns of Ca²⁺ and Na⁺ are illustrated. The other slow variables were frozen ([ATP] = 3,300 μM, [IP₃] = 3 μM, and [Ca²⁺]_ER = 50 μM) at constant levels to eliminate other mechanism of [Ca²⁺]_c oscillations. All other parameter settings are as in Ref. 51. A: V_P. B: [Ca²⁺]_c. C: [Na⁺]_c. D: I_NaK.