Figure 6.

Effect of changing g_j on action potential conduction velocity (θ). (A) Ventricular θ slows from a maximum of 64 to <1 cm/s as g_j is reduced from 2500 to <5 nS. At high g_j values, no variations in θ are observed as a result of V_j-dependent gap-junction inactivation. (B) Discrepancies in θ are apparent at low resting g_j values, depending on the gap-junction inactivation rates that are utilized, and block develops at higher values than if g_j is kept constant during action potential propagation. (C) The optimal dose of 100 nM rotigaptide can completely prevent the conduction slowing produced by V_j-dependent g_j gating (black dotted arrow) via a reduction in the inactivation kinetics (solid grey arrow) coupled with a 10% increase in resting g_j (dashed grey arrow). A 20% increase in resting g_j is also sufficient to reverse the conduction slowing without alteration of the g_j inactivation kinetics (dotted grey arrow).