P2X3 - "Activation and inhibition of P2X3 channels recorded on the Patchliner"
Patchliner application note: (0.6 MB)
Cells were engineered and kindly provided by Axxam S.p.A., Milan.
P2X receptors are ligand-gated ion channels that open in response to extracellular ATP. They are permeable to small monovalent cations, some having significant divalent or anion permeability. P2X receptors are found on many cell types including smooth muscle cells, sensory neurones, epithelia, bone and leukocytes. A role for P2X receptors has been suggested in transmission of thermal stimuli, chemosensory signalling, taste and pain. To date, 7 P2X receptor genes have been cloned and studied in heterologous expression systems. Functional receptors are trimeric, which can be homomeric or heteromeric. The P2X2 and P2X3 receptors can function either as homomers or as P2X2/3 heteromers. When expressed together, a mixture of P2X2 and P2X3 homomers as well as P2X2/3 heteromers are likely to exist, which may be distinguished through their biophysical and pharmacological properties. Both P2X3 homomers and P2X2/3 heteromeric receptors have been implicated in nociception and pain signalling and may be important therapeutic targets for analgesic drugs. The P2X3 and P2X2/3 receptor antagonist MK-7264 (gefapixant), has recently progressed to Phase III trials for refractory or unexplained chronic cough.
Here we present data collected on the Patchliner showing activation and inhibition of P2X3 currents expressed in CHO cells with rapid and brief application of ligand (using the stacked solution approach). αβ-methylene ATP (αβ-MeATP) activated P2X3 receptors in a concentrationdependent manner with an EC50 value similar to those in the literature. P2X3 receptors could be repetitively activated by αβ-MeATP and blocked by A-317491 with an IC50 value in good agreement with the literature.