FIGURE 7.

Role of L-type Ca²⁺ channels in model simulations. (A) Average Ca²⁺ (upper trace) and membrane potential response (lower trace) to increasing IP₃ in the same simulation as for Fig. 6, with L-type Ca²⁺ channels blocked. (B) Regions marked with numbered bars in panel A shown in further detail. (B (1a)) Average Ca²⁺ changes in each cell shows asynchronous Ca²⁺ transients across the syncytium. (B (1b)) Space-time plot shows asynchronous Ca²⁺ transients and local Ca²⁺ waves within cells. (B (2a)) With increasing stimulation (i.e., [IP₃]), the frequency of Ca²⁺ transients is increased but synchronous pacemaker Ca²⁺ transients do not arise. (B (2b)) Space-time plot shows further details of the store Ca²⁺ transients. Timescale bar in B (2b) applies to all traces and space-time plots in panel B. Ca²⁺ scale bar applies to all traces. All voltage and Ca²⁺ scale bars represent normalized values.