title: Effect of N-feruloyl tyramine (an analogue of tyramine) on inwardly rectifying potassium channel in frog ventricular myocytes.
abstract: Electrophysiological effects of N-feruloyl tyramine (NFT), an analogue of tyramine, on potassium currents in frog ventricular myocytes were examined using single-channel recording and whole-cell voltage clamp technique. Extracellular application of NFT induced a concentration-dependent decrease of macroscopic inward rectifier potassium current (iK1) with ID50 of 198 microM, while tyramine (100 microM) was ineffective in producing an inhibitory effect on iK1. NFT reduced the mean open time of iK1 to 1.3 ms from 3.1 ms in control without affecting the amplitude of single-channel conductance. It is indicated that boi containing NFT produces a prolongation of the plateau phase caused by the suppression of inwardly rectifying K channel. Thus, this prolongation may induce an increase in the inflow of Ca ions, which in turn leads to a positive inotropic effect.
authors.affiliation: Department of Physiology, Hiroshima University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Munemori
authors.forename: K
authors.initials: K
authors.lastname: Yamaoka
authors.forename: I
authors.initials: I
authors.lastname: Yusuf
authors.forename: K
authors.initials: K
authors.lastname: Sumii
authors.forename: H
authors.initials: H
authors.lastname: Otsuka
authors.forename: K
authors.initials: K
authors.lastname: Yamasaki
mesh_terms: D000818:Animals; D003373:Coumaric Acids / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D011892:Rana catesbeiana; D014439:Tyramine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016276:Ventricular Function
chemical_list: D003373:Coumaric Acids; D015221:Potassium Channels; C074004:feruloyltyramine; D014439:Tyramine