A novel enhancing effect of clofilium on transient outward‐type cloned cardiac K⁺ channel currents

Abstract

2 Extracellular application of clofilium slightly inhibited the current at + 60 mV from a holding potential of -80 mV. However, it unexpectedly enhanced the current from a holding potential of -60 mV in a dose-dependent manner (219 ± 39% of control at 100 AM).3 This enhancement is probably due to an increase in the ratio of channels in the resting state during steady depolarization, since clofilium shifted the inactivation curve in the depolarizing direction. 4 LY97119, a tertiary ammonium analogue of clofilium, did not exhibit this enhancing effect but only inhibited the current. 5 Clofilium may be useful for the study of channel inactivation because this type of phenomenon has not been reported for any other drug.

The pharmacological properties of K+ currents from rabbit isolated aortic smooth muscle cells

“…Halliday et a! Pharmacology of K+ channels in aortic myocytes 3147 transient current in cloned cardiac potassium channels (Kobayashi et al, 1995). In this case, clofilium enhanced the transient current from a holding potential of -60 mV, as well as accelerating current inactivation.…”