Objective
Ligand-gated ion channels are of particular
interest to the pharmaceutical industry for the treatment of diseases from a
variety of therapeutic areas including CNS disorders, respiratory disease and
chronic pain. Ligand-gated ion channels have historically been investigated
using fluorescence-based and low throughput patch-clamp techniques. However, with
the development of the Qube 384 automated patch-clamp system, the rapid
exchange of liquid and direct measurement of ion channel currents on a
millisecond timescale is now possible at a greater throughput than previously possible.
Here, we have used the Qube platform to develop assays against two ligand-gated
families: 1) the P2X receptor and 2) the GABA receptor families. The P2X family
is comprised of 7 family members, which are cation permeable and gated by the
binding of extracellular ATP. We have assessed both agonist and antagonist
pharmacology of 4 members of the P2X family, P2X1, P2X2,
P2X3 and P2X4, as well as two species homologs, rP2X3
and gpP2X3. The GABAA
α1β3γ2 receptor is a
chloride permeable ion channel gated by the binding of GABA. We utilized
stacked liquid addition to assess the open state kinetics of the channel and to
investigate the effects of a positive allosteric modulator on channel function.
As such, we have successfully characterized and developed assays for both the
P2X receptor and GABA receptor families and present EC/IC50 data
for antagonists and positive allosteric modulators.
