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. 2007 Mar 16;92(11):3901–3914. doi: 10.1529/biophysj.106.102400

FIGURE 2.

FIGURE 2

TBA block characteristics. (A) Effect of TBA on the fraction of blocked channels. Average blocking dose-response as a function of TBA concentration obtained from nine patches. Block by TBA was completely reversible. The Hill equation (Eq. 1) was fitted to the data with parameters n = 0.89 and KD = 280 μM. (B) Voltage dependence of KD measured from five patches. The continuous line is the predicted KD as a function of voltage from the permeant blocker model shown in Scheme 1. The rate constants used are: k1 = 5 × 105 M−1s−1 × exp(0.99eoV/kT), k−1 = 90s−1 × exp(−0.13eoV/kT), k2 = 163s−1 × exp(0.02eoV/kT). These rate constants were constrained to be similar to those obtained from data on TBA kinetics of block shown in Fig. 6. (C) The fraction of blocked channels as a function of voltage in the presence of TBA. Increasing concentrations are indicated by the following symbols (in μM): ○, 50; □, 100; ▵, 250; ⊕, 500; ▿, 1000; ⋄, 2500; ⊗, 5000; ▹, 10,000. Continuous lines are the predictions from the same model and parameters used in (B).