Intracellular QX-314 blocks the hyperpolarization-activated inward current Iq in hippocampal CA1 pyramidal cells.
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.
Perkins
K L
KL
Department of Pharmacology, State University of New York Health Science Center, Brooklyn 11203, USA.
Wong
R K
RK
D000818:Animals; D004553:Electric Conductivity; D004594:Electrophysiology; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000187:drug effects; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects* / Q000502:physiology*
C012647:QX-314; D008012:Lidocaine