Details

Autor(en) / Beteiligte

• Jeong, Imju
• Yoon, Shin Hee
• Hahn, Sang June

Titel

Effects of dapoxetine on cloned Kv1.5 channels expressed in CHO cells

Ist Teil von

• Naunyn-Schmiedeberg's archives of pharmacology, 2012-07, Vol.385 (7), p.707-716

Ort / Verlag

Berlin/Heidelberg: Springer-Verlag

Erscheinungsjahr

2012

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The effects of dapoxetine were examined on cloned Kv1.5 channels stably expressed in Chinese hamster ovary cells using the whole-cell patch clamp technique. Dapoxetine decreased the peak amplitude of Kv1.5 currents and accelerated the decay rate of current inactivation in a concentration-dependent manner with an IC 50 of 11.6 μM. Kinetic analysis of the time-dependent effects of dapoxetine on Kv1.5 current decay yielded the apparent association ( k + 1 ) and dissociation ( k − 1 ) rate constants of 2.8 μM −1  s −1 and 34.2 s −1 , respectively. The theoretical K D value, derived by k − 1 / k + 1 , yielded 12.3 μM, which was reasonably similar to the IC 50 value obtained from the concentration–response curve. Dapoxetine decreased the tail current amplitude and slowed the deactivation process of Kv1.5, which resulted in a tail crossover phenomenon. The block by dapoxetine is voltage-dependent and steeply increased at potentials between −10 and +10 mV, which correspond to the voltage range of channel activation. At more depolarized potentials, a weaker voltage dependence was observed ( δ  = 0.31). Dapoxetine had no effect on the steady-state activation of Kv1.5 but shifted the steady-state inactivation curves in a hyperpolarizing direction. Dapoxetine produced a use-dependent block of Kv1.5 at frequencies of 1 and 2 Hz and slowed the time course for recovery of inactivation. These effects were reversible after washout of the drug. Our results indicate that dapoxetine blocks Kv1.5 currents by interacting with the channel in both the open and inactivated states of the channel.