PMID: 9446697Apr 4, 1998Paper

Verapamil block of the delayed rectifier K current in chick embryo dorsal root ganglion neurons

Pflügers Archiv : European journal of physiology
C TrequattriniF Franciolini

Abstract

We have used the patch-clamp method in the whole-cell configuration to investigate the mechanism of block of the delayed rectifier K current (IDRK) by verapamil in embryonic chick dorsal root ganglion (DRG) neurons. Verapamil induced a dose-dependent decay of the current, without altering its activation kinetics. This observation, together with the good description of IDRK time course at various blocker concentrations with the computer simulation of a three-state chain model (closed left and right arrow open left and right arrow open-blocked), indicates that verapamil acts as a state-dependent, open-channel blocker. To account for the double-exponential time course of recovery from block, this minimal kinetics scheme was expanded to include a closed-blocked state resulting from channel closure (at hyperpolarized voltages) with verapamil still bound to it. The apparent block and unblock rate constants assessed from verapamil-induced current decay in the presence of external Na were 0.95 +/- 0.05 ms-1mM-1 and 0.0037 +/- 0.0016 ms-1, respectively. When external Na was replaced by K, only the unblock rate constant changed, to 0.02 +/- 0.009 ms-1. Under these ionic conditions it was also observed that the recovery from block was mod...Continue Reading

Citations

Oct 26, 1999·Trends in Neurosciences·O H Petersen, J M Cancela
Jun 26, 2009·Critical Care Medicine·Daniel I Sessler
Apr 1, 1999·Annual Review of Physiology·M F Romero, W F Boron

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