Figure 12.

In simulations with the PBM, ATP/ADP invariance to changes in glucose is lost when $g_{\text{K}\left(\text{Ca}\right)}$ is increased from 10 pS, which yields slow bursting (period ∼6 min) driven by K(ATP) current, to 300 pS, which yields faster bursting driven mainly by K(Ca) current (period ∼2 min). (A) Simulated slow bursting trajectory with $G=8$ mM (black) and $G=13$ mM (gray) glucose projected into the $V$ versus ATP/ADP plane. The projections are nearly identical, in contrast to the case with faster bursting, where the trajectory corresponding to $G=8$ mM (blue) is to the left of that corresponding to $G=13$ mM (cyan). (B) Curves of saddle-node bifurcations (SNB) and homoclinic bifurcations (HM) in the c_ER versus ATP/ADP plane are identified using squares and triangles, respectively. The black curves correspond to slow bursting, and the blue correspond to faster bursting. Also shown are projections of slow bursting at 8 mM and 13 mM glucose (black and gray loops, respectively) and of the faster bursting at 8 mM and 13 mM glucose (blue and cyan loops, respectively). To see this figure in color, go online.