Figure 3. Effects of TEA_o and K_o⁺ on OI. (A) Left panel, I_K evoked by 0 mV/7sec pulse applied either in the absence (Na_o) or in the presence of 15 mM TEA_o, as indicated. Middle trace: I_K with TEA scaled to control peak I_K. OI follows the time course (Fig. 1): Ik(t)/Io = Af*exp(−t/τ_f,_OI) + As*exp(−t/τ_s,_OI) + C; Io is peak I_K; τ_f,OI,TEA = 0.33 ± 0.07, τ_s,OI,TEA = 1.2 ± 0.22, Af_TEA = 0.28 ± 0.07, As_TEA = 0.65 ± 0.07, C_TEA = 0.06 ± 0.02. Right panel, inactivation time constants measured either in Na_o or in 15 mM TEA_o. TEA_o significantly decreases both constants (p < 0.05). (B) Left panel, I_K evoked by a +20mV/7sec pulse applied in either Na_o or 100 K_o solutions, as indicated. Middle trace: I_K in 100 K_o scaled to control peak I_K. Right panel, inactivation time constants, as indicated. (C) Superposed I_K recorded in either 100 mM K⁺_o or in 100 K⁺_o plus 15 mM TEA_o. (D) OI time course. The lines are the least squares fit of OI of traces as in (A and B): 15TEA (dotted line, parameters as above, n = 6); 100 Ko (dashed line, n = 6): τ_f,OI,K = 0.4 ± 0.05 sec, τ_s,OI,K = 1.5 ± 0.04 sec, Af_K = 0.34 ± 0.13, As_K = 0.64 ± 0.12, C_K = 0.02 ± 0.008; Na_o (solid line): τ_f,_OI,Na = 0.6 ± 0.05sec, τ_s,_OI,Na = 2.1 ± 0.22, Af_Na = 0.3 ± 0.02, As_NA = 0.68 ± 0.03, C_Na = 0.05 ± 0.01.