Characterization of the inhibitory action of compounds on NaV1.2 sodium channels by using an automated patch-clamp assay
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1
Richter Gedeon Ltd., Hungary
Automated patch-clamp techniques offer a reliable way of testing interaction of drug molecules and ion channel receptors in pharmacology research. The QPatch-16 system utilizes suspended cells and uses planar electrodes in a completely automated way, measuring the responses of up to 16 cells, simultaneously. Compounds with inhibitory action on sodium channels have a clinically advantageous feature as they preferentially block sodium channels of over-active neurons involved in pathological processes, while leaving normal physiological functions relatively intact. An ideal sodium channel blocker has therefore, much higher affinity to the inactivated than the resting conformation of the sodium channel protein. This state-dependency of sodium channel blocker compounds was investigated by the QPatch automated patch-clamp system on CHO cells stably expressing the sodium channel alpha subunit NaV1.2. The holding potential dependence of the available whole-cell currents was determined between -25 and -100 mV at 5 mV steps at different drug concentrations, ranging from 0.01-100 μM. V1/2 was defined as the potential where 50% of the channels were inactivated. IC50 for blocking sodium currents obtained at V1/2 was used for characterizing the potency of each compound. Furthermore, IC50 values in the presence of various drug concentrations were calculated using inhibition data extracted from the inactivation curves. After plotting IC50s against holding potential values on a semi-logarithmic scale a linear equation was fitted to the data and the slope factor was used to quantitatively characterize the state-dependence of each compound. Slope factors of therapeutically used sodium channel inhibitors ranged from 50-80. Our results indicate that this analysis offers an easy, quick and reliable way for evaluating the state-dependent sodium channel inhibitory activity of compounds.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Abstracts
Citation:
Farkas
B,
Kocsis
P,
Fodor
L and
Tarnawa
I
(2010). Characterization of the inhibitory action of compounds on NaV1.2 sodium channels by using an automated patch-clamp assay.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00199
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Received:
03 May 2010;
Published Online:
03 May 2010.
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Correspondence:
Bence Farkas, Richter Gedeon Ltd., Budapest, Hungary, b.farkas@richter.hu