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Updated: Jul 18, 2026

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels
Published on: January 27, 2013
Torilin from Torilis japonica (Houtt.) DC. blocks hKv1.5 channel current
Yong Geun Kwak1, Dae Keun Kim, Tian-Ze Ma
1Department of Pharmacology, Chonbuk National University Medical School, Chonju, 561-756, Korea.
Abstract:
Torilin was purified from Torilis japonica (Houtt.) DC., and its effects on a rapidly activating delayed rectifier K+ channel (hKv1.5), cloned from human heart and stably expressed in Ltk- cells, as well as the corresponding K+ current (the ultrarapid delayed rectifier, I(KUR)) were assessed in human atrial myocytes. Using the whole cell configuration of the patch-clamp technique, torilin was found to inhibit the hKv1.5 current in time and voltage-dependent manners, with an IC50 value of 2.51+/-0.34 microM at +60 mV. Torilin accelerated the inactivation kinetics of the hKv1.5 channel, and slowed the deactivation kinetics of the hKv1.5 current, resulting in a tail crossover phenomenon. Additionally, torilin inhibited the hKv1.5 current in a use-dependent manner. These results strongly suggest that torilin is a type of open-channel blocker of the hKv1.5 channel.
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