Munemori M, Yamaoka K, Yusuf I, Sumii K, Otsuka H, Yamasaki K
Department of Physiology, Hiroshima University School of Medicine, Japan.
Hiroshima J Med Sci. 1996 Mar;45(1):31-5.
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.
使用单通道记录和全细胞膜片钳技术，研究了酪胺类似物N-阿魏酰酪胺（NFT）对蛙心室肌细胞钾电流的电生理效应。细胞外施加NFT可引起宏观内向整流钾电流（iK1）浓度依赖性降低，半数抑制浓度（ID50）为198微摩尔，而酪胺（100微摩尔）对iK1无抑制作用。NFT将iK1的平均开放时间从对照时的3.1毫秒缩短至1.3毫秒，而不影响单通道电导幅度。结果表明，含NFT的生物制剂通过抑制内向整流钾通道，使平台期延长。因此，这种延长可能导致钙离子内流增加，进而产生正性肌力作用。
