Cells were pretreated with either vehicle alone (0.1% DMSO) or 10 μm WT for 15 min at 37° before the addition of either buffer or 1 mm Oxo-M for an additional 30 min. Reactions were terminated by the addition of ice-cold buffer A, and cell surface mAChR number was monitored by means of [³H]NMS binding. Values are reported as the specific binding of [³H]NMS (fmol/mg protein) and as the Oxo-M induced loss of cell surface [³H]NMS binding sites (percentage) relative to controls. Results from one of two experiments are shown.