Ketanserin Inhibits the Transient Outward Current in Rabbit Ventricular Myocytes

Abstract

The effects of ketanserin on the calcium-independent component of the transient outward potassium current (7to) was investigated in isolated rabbit ventricular myocytes using the whole-cell patch-clamp technique. Ketanserin concentration-dependently (0.1–100 μM) reduced Ito (IC50 2.25 ± 2.2 μM; Hill coefficient, nH 0.91), and decreased both the fast and slow 7to inactiva-tion time constants so that the decay of the peak outward current was significantly accelerated. Our results indicate that, in addition to its antagonist activity on 5HT2A/C receptors, ketanserin reduces the calcium-independent component of Ito. Blockade of Ito could explain the proar-rhythmic properties of ketanserin in vivo.