FIG. 2.

Automaticity in identical cells for high $I_{K1}$ current at the cleft. The time series for the (a) lateral segment voltage, (b) cleft voltage, (c) cleft potassium concentration, $I_{K1}$ at the (d) lateral segment and (e) junctional membrane, sodium current $I_{Na}$ at the (f) lateral segment and (g) junctional membrane, and (h) lateral segment slow-inward current $I_{si}$, for the junctional membrane fraction of $I_{K1}$ ( $f_{K1}$) of 0.7 (black) and 0.9 (green). Higher $f_{K1}$ triggered automaticity and synchronized APs in both cells, due to cleft potassium accumulation, increasing the resting potential to trigger inward $I_{si}$.