Figure 3.

Isoprenaline can change the modes of the late sodium-channel current. The duration of depolarization was prolonged to 700 ms. (A) Control: brief opening of the late sodium-channel currents were observed once in a while in the late clamping time. (B) After adding isoprenaline (3×10⁻⁷ mol/L), the frequency of sodium channel opening was increased substantially. The open modes of the late sodium-channel current were identified as: brief opening, scattered opening, long opening and burst mode. The first three traces in group B show the burst mode of the sodium channel. (C and D) The averaged currents from group A and B. There was a small and slow-decaying inward current in trace D.