Sulfur dioxide derivative modulation of potassium channels in rat ventricular myocytes

The effects of sulfur dioxide (SO2) derivatives (bisulfite and sulfite, 1:3 M/M) on voltage-dependent potassium current in isolated adult rat ventricular myocyte were investigated using the whole cell patch–clamp technique. SO2 derivatives (10 μM) increased transient outward potassium current (Ito) and inward rectifier potassium current (IK1), but did not affect the steady-state outward potassium current (Iss). SO2 derivatives significantly shifted the steady-state activation curve of Ito toward the more negative potential at the Vh point, but shifted the inactivation curve to more positive potential. SO2 derivatives markedly shifted the curve of time-dependent recovery of Ito from the steady-state inactivation to the left, and accelerated the recovery of Ito from inactivation. In addition, SO2 derivatives also significantly change the inactivation time constants of Ito with increasing fast time constant and decreasing slow time constant. These results indicated a possible correlation between the change of properties of potassium channel and SO2 inhalation toxicity, which might cause cardiac myocyte injury through increasing extracellular potassium via voltage-gated potassium channels.