Effect of GLG-V-13, a Class III antiarrhythmic agent, on potassium currents in rabbit ventricular myocytes

The effects of a new Class III antiarrhythmic drug, GLG-V-13, on the 4-amin opyridine sensitive transient outward current, on the inward rectifier pota ssium current, on the ATP sensitive potassium current and on the rapid and slow components of the delayed rectifier potassium current were studied in single rabbit ventricular myocytes using the whole-cell voltage-damp techni que. GLG-V-13 blocked the rapid component of the delayed rectifier potassiu m current in a dose-dependent manner, with an estimated EC50 value of 0.36 mu M. At high concentration, the slow component of the delayed rectifier po tassium current was also depressed by the drug (40% effect at 10 mu M conce ntration). The transient outward current, the inward rectifier potassium cu rrent and the ATP sensitive potassium current were not influenced by GLG-V- 13, even at 10 mu M concentration. Thus, GLG-V-13 blocks predominantly the rapid component of the delayed rectifier potassium current which may play a significant role in the prolongation of repolarization by the drug in vent ricular tissue. (C) 2000 Elsevier Science Inc.