Figure 4.

BK current differentially contributes to AP repolarization in BK_i and BK_s cells. (A) APs elicited by a 100-pA depolarizing current pulse are shown for identified BK_i (left) and BK_s (right) RCCs in both control and 0-Ca²⁺ saline, as indicated. The extracellular saline contained 200 nM apamin. (B) The simulated waveforms of APs elicited by 100-pA depolarizing current pulses are shown for a model BK_i (left) cell and a model BK_s (right) cell in control and 0 Ca²⁺, as indicated. SK currents were removed in all cases. (C–E) Individual current components (Na, Kv, BK, and Ca) appearing in a single AP are shown for a model BK_i (left) cell and a model BKs (right) cell, for control saline (C), 0 Ca²⁺ saline (D), and with nominal 100 nM CTX (0.2 BK; E).