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) oil voltage-dependent potassium current in isolated adult rat ventricular myocyte were investigated using the whole cell patch-clamp technique. SO, derivatives (10 mu m) increased transient outward potassium current (I-to) and inward rectifier potassium current (I-KI), but did not affect the steady-state outward potassium current (I-ss). SO2 derivatives significantly shifted the steady-state activation curve of I-to toward the more negative potential at the V-h point, but shifted the inactivation curve to more positive potential. SO, derivatives markedly shifted the curve of time-dependent recovery of I-to from the steady-state inactivation to the left, and accelerated the recovery of I-to from inactivation. In addition, SO2 derivatives also significantly change the inactivation time constants of I-to 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. (c) 2005 Elsevier Inc. All rights reserved.