Intracellular QX-314 blocks the hyperpolarization-activated inward current Iq in hippocampal CA1 pyramidal cells

J Neurophysiol. 1995 Feb;73(2):911-5. doi: 10.1152/jn.1995.73.2.911.


1. Whole cell voltage-clamp recordings (access resistance < or = 12 M omega) from CA1 pyramidal cells in the guinea pig hippocampal slice revealed a hyperpolarization-activated inward current with an inward tail upon repolarization. The current activation range extended from approximately -50 mV to -130 mV, with half-activation at -86 mV. This current was identified as the q current (Iq). 2. Intracellular QX-314 (5 or 10 mM), a quaternary derivative of lidocaine, blocked Iq completely throughout its activation range. 3. There is a growing realization that Iq may be responsible for the pacemaker depolarization in cells that display rhythmic calcium spikes. Because QX-314 blocks Iq completely, it could be used to test whether Iq is essential to this oscillatory activity.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Electric Conductivity
  • Electrophysiology
  • Guinea Pigs
  • Hippocampus / drug effects*
  • Hippocampus / physiology*
  • In Vitro Techniques
  • Intracellular Membranes / drug effects
  • Lidocaine / analogs & derivatives*
  • Lidocaine / pharmacology
  • Pyramidal Cells / drug effects*
  • Pyramidal Cells / physiology*


  • QX-314
  • Lidocaine