Development and validation of a secondary screening assay for TRPM8 antagonists using QPatch HT

QPatch HT is an automated patch clamp system with high data quality/content and greatly increased throughput over conventional patch clamp methods. To determine whether this platform is suitable for secondary screening of antagonists of TRPM8, a cold- and menthol-activated ion channel that belongs to the transient receptor potential channel family, we used QPatch HT to test a set of chemically diverse compounds identified as TRPM8 antagonists by FLIPR and conventional patch clamp. We found that most compounds exhibited slower inhibition kinetics compared with conventional patch clamp, requiring multiple applications to reach steady-state inhibition. For most compounds, there was a relatively small (< or =4-fold) right shift in potency compared with conventional patch clamp. Nonetheless, the compound potencies obtained from QPatch HT exhibited a highly significant correlation with those from either conventional patch clamp (r(2) = 0.98) or FLIPR (r(2) = 0.97), over a wide range of concentrations and cLogP values (approximately 4 orders of magnitude) and with virtually identical rank-order potency. The throughput by QPatch HT was at least 10-fold higher than that obtained by conventional patch clamp. Our results validate the use of QPatch HT for secondary screening of TRPM8 antagonists and, along with other recent studies, illustrate its utility as an important tool for ion channel drug discovery.