A GABA Ligand Gated Ion Channel Screen - Results and Best Practices


The GABAA receptors belong to a family of ligand-gated ion channels medi- ating fast synaptic transmission. They are drawing great attention in the phar- maceutical industry due to their potential role in the development of new therapeutics affecting anxiety, sleep disorders, and muscle relaxation. How- ever, ligand-gated ion channel screening has been hampered by the lack of suitable high throughput electrophysiology platforms. The search for subtype-selective drugs for GABAA channels has been hampered by the lack of suitable high throughput electrophysiology platforms with the ability to in- terrogate ligand

gated ion channels.

Here we present the use of a novel electrophysiology screening platform in- tegrating a microfluidics network for the study of GABAA receptor pharmacol- ogy. This platform features fast (100ms) solution exchange coupled with si- multaneous data recording. A novel assay could monitor GABA response in real time, and obtain a 3 point EC50 dose curve within 1 minute.

The GABAA 􏰈1/􏰊3/􏰌2 expressing HEK cells from Millipore were used for this study. The channel was targeted with agonists, including GABA and musci- mol, inhibitors (picrotoxin, bicuculline, and gabazine), and positive modula- tors, including diazepam, zolpidem and chlordiazepoxide. The positive modulators produced concentration dependent augmentation of the GABA EC20 response. The pharmacology data determined using this method was consistent with the literature values obtained using other platforms. Statisti- cal data for inter and intra-plate reproducibility, current stability, and Z’-values, is used to validate this approach.