Characterization of compounds on nicotinic acetylcholine receptor alpha7 channels using higher throughput electrophysiology

Abstract

Alpha7 nicotinic acetylcholine receptor channels are important ligand-gated ion channels that are fast desensitizing, cation selective and have been implicated in the pathophysiology of schizophrenia and Alzheimer's disease. We report here high quality α7 parallel patch clamp recordings using the QPatch automated patch clamp system. The QPatch patch clamps up to 48 cells in parallel with the same high fidelity as conventional patch clamp. EC 50 and IC 50 values were comparable to values obtained with conventional patch clamp. The EC 50 value for acetylcholine (ACh) on the QPatch with area under the curve (AUC) analysis was 26 μM compared to a value of 29 μM determined from conventional patch clamp experiments. Sequential additions of ACh can be made with minimal decay of the peak amplitude. The competitive α7 antagonist methyllycaconitine (MLA) blocked currents with an IC 50 value of 0.25 nM which is similar to published IC 50 values for MLA. Finally, two different classes of positive allosteric modulators represented by PNU-120596 and NS-1738 elicited characteristic responses, thus allowing accurate characterization of modulation and measurements of potency. These results demonstrate that α7 nicotinic acetylcholine receptor channels can be studied reliably in a higher throughput, parallel manner with the QPatch automated patch clamp system.