Comparison of hERG activity measured by patch clamp and 3H-dofetilide binding in cells maintained at different growth temperatures. CHO hERG cells grown at 37°C were split and kept subconfluent at 37, 30 or 27°C for 3 d (A,B). HEK293 hERG was split and kept at 37 or 30°C for 24 h (C). Mean tail currents recorded by patch clamping (IonWorksHT) from 4 independent experiments, 32–64 cells were patched for each data point in every experiment (A). 3H-dofetilide binding activity for CHO hERG and HEK hERG membrane preps respectively (B,C). Each data point was from 2 independent experiments, each of 3 repeats. Background (non-specific) binding was measured in the presence of an excess amount of non-radioactive dofetilide. Specific binding (open bars) was calculated as the total counts minus background counts and the total: background ratio (diamonds) was calculated as the total counts divided by the background counts.