Characterization of Compound-Specific, Concentration-Independent Biophysical Properties
of Sodium Channel Inhibitor Mechanism of Action Using Automated Patch-Clamp Electrophysiology
Hungarian Brain Research Program(KTIA-NAP-13-2-2014-002)
(GINOP-2.3.2-15-2016-00051)
We have developed an automated patch-clamp protocol that allows high information content
screening of sodium channel inhibitor compounds. We have observed that individual
compounds had their specific signature patterns of inhibition, which were manifested
irrespective of the concentration. Our aim in this study was to quantify these properties.
Primary biophysical data, such as onset rate, the shift of the half inactivation voltage,
or the delay of recovery from inactivation, are concentration-dependent. We wanted
to derive compound-specific properties, therefore, we had to neutralize the effect
of concentration. This study describes how this is done, and shows how compound-specific
properties reflect the mechanism of action, including binding dynamics, cooperativity,
and interaction with the membrane phase. We illustrate the method using four well-known
sodium channel inhibitor compounds, riluzole, lidocaine, benzocaine, and bupivacaine.
Compound-specific biophysical properties may also serve as a basis for deriving parameters
for kinetic modeling of drug action. We discuss how knowledge about the mechanism
of action may help to predict the frequency-dependence of individual compounds, as
well as their potential persistent current component selectivity. The analysis method
described in this study, together with the experimental protocol described in the
accompanying paper, allows screening for inhibitor compounds with specific kinetic
properties, or with specific mechanisms of inhibition.