These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Inhibition of HERG K+ current and prolongation of the guinea-pig ventricular action potential by 4-aminopyridine.
    Author: Ridley JM, Milnes JT, Zhang YH, Witchel HJ, Hancox JC.
    Journal: J Physiol; 2003 Jun 15; 549(Pt 3):667-72. PubMed ID: 12740430.
    Abstract:
    4-Aminopyridine (4-AP) has been used extensively to study transient outward K+ current (ITO,1) in cardiac cells and tissues. We report here inhibition by 4-AP of HERG (the human ether-à-go-go-related gene) K+ channels expressed in a mammalian cell line, at concentrations relevant to those used to study ITO,1. Under voltage clamp, whole cell HERG current (IHERG) tails following commands to +30 mV were blocked with an IC50 of 4.4 +/- 0.5 mM. Development of block was contingent upon HERG channel gating, with a preference for activated over inactivated channels. Treatment with 5 mM 4-AP inhibited peak IHERG during an applied action potential clamp waveform by ~59 %. It also significantly prolonged action potentials and inhibited resurgent IK tails from guinea-pig isolated ventricular myocytes, which lack an ITO,1. We conclude that by blocking the alpha-subunit of the IKr channel, millimolar concentrations of 4-AP can modulate ventricular repolarisation independently of any action on ITO,1.
    [Abstract] [Full Text] [Related] [New Search]