title: Torilin from Torilis japonica (Houtt.) DC. blocks hKv1.5 channel current.
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.
authors.affiliation: Department of Pharmacology, Chonbuk National University Medical School, Chonju, 561-756, Korea.
authors.forename: Yong Geun
authors.initials: YG
authors.lastname: Kwak
authors.forename: Dae Keun
authors.initials: DK
authors.lastname: Kim
authors.forename: Tian-Ze
authors.initials: TZ
authors.lastname: Ma
authors.forename: Sun-Ah
authors.initials: SA
authors.lastname: Park
authors.forename: Hoon
authors.initials: H
authors.lastname: Park
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Jung
authors.forename: Dong-Jin
authors.initials: DJ
authors.lastname: Yoo
authors.forename: Jae Soon
authors.initials: JS
authors.lastname: Eun
mesh_terms: D000818:Animals; D019661:Apiaceae / Q000737:chemistry*; D002460:Cell Line; D002850:Chromatography, Gel / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005638:Fruit / Q000737:chemistry; D006801:Humans; D051666:Kv1.5 Potassium Channel / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D015394:Molecular Structure; D018408:Patch-Clamp Techniques / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000494:pharmacology; D045789:Sesquiterpenes, Guaiane / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D014162:Transfection
chemical_list: D051666:Kv1.5 Potassium Channel; D010936:Plant Extracts; D026902:Potassium Channel Blockers; D045789:Sesquiterpenes, Guaiane; C112694:torilin