FIGURE 9.

Interaction with partially inactivated channels. (A) Illustrated are relative currents amplitudes in relation to the applied concentration of TIC10 upon partial inactivation of the channels of one representative cell (out of five experiments). For evaluation data were fitted with Eq. 1, giving K_app. In order to estimate the affinity for the inactivated state (K_i), the current amount of non-inactivated channels (h) was considered according to Eq. 7, resulting in a mean K_i of 4.7 ± 1.3 µM (N = 5). Data evaluation (relation of test-pulse to control pulse) was restricted to experiments where the current amplitudes obtained from mere control solution did not deviate by more than 3%. (B) Experimental scheme. From a holding potential of −140 mV conditioning pre-pulses to a potential of about half-maximal inactivation (V₅₀) were applied for 20 s before the test-pulse to −20 mV was executed. This protocol was executed a second time, either in the presence of control solution or different concentrations of TIC10.