Figure 1. Inhibitory effect of amiodarone on I _KAS.

(A) Representative superimposed whole-cell I _K traces obtained by the pulse protocol shown in the inset. The pipette solution contained 1 µM free Ca²⁺ to activate I _KAS. (B) Superimposed I_K traces in the presence of 10 µM amiodarone. (C) Superimposed I _K traces after adding 100 nM apamin to the same preparation. (D) Current-voltage (I-V) relationships obtained in the absence and presence of 10 µM amiodarone, then 100 nM apamin. I _K was measured between 280 ms and 290 ms of the test pulse, and plotted against membrane potentials. Similar results with 10 µM amiodarone were observed in 5 cells.