Figure 2.

Characterization of Areca alkaloids analogs on M₁ and M₃ acetylcholine (AChR) expressed in Xenopus oocytes. The structures of the analogs, 1-(4-methylpiperazin-1-yl) ethanone (MPA), 4-acetyl-1,1-dimethylpiperazin-1-ium (DMPA), and 1-(4-ethylpiperazin-1-yl) ethanone (EPA) are shown accompanying the corresponding data. A two-application protocol as described for Supplementary Figure S1 was used to characterize these ligands for their effects on cells expressing M₁ and M₃ AChR. Test compounds were applied at 10 µM, and then after a 3-min wash period 10 µM acetylcholine was applied to determine whether the initial application was able to desensitize the receptor/channel system and decrease or eliminate further responses.