Figure 4.

Nicotinic activity of the isoarecolone analogs (see Figure 3 for structures). After obtaining two acetylcholine control responses, 100 µM applications of 1-(4-methylpiperazin-1-yl) ethanone, 4-acetyl-1,1-dimethylpiperazin-1-ium, and 1-(4-ethylpiperazin-1-yl) ethanone were made to oocytes expressing the low sensitivity form of α4β2 (α4(3)β2(2)), the high sensitivity form of α4β2 (α4(2)β2(3)), or α7. Analog-evoked responses were calculated relative to the peak currents (α4β2 subtypes) or net charge (α7 receptors) of the ACh controls. Control ACh concentrations were 10 µM, 60 µM, and 100 µM for α4(2)β2(3), α7, and (α4(3)β2(2), respectively. An α4β2 dimer was co-expressed with monomeric α4 or β2³² to yield the α4β2 subtypes indicated. Additionally, the α7-expressing cells were tested with co-applications of 10 µM PNU-120596 and 100 µM of the analogs. Those data, normalized to the responses of the same cells to 60 µM ACh alone, are plotted relative to y-axis on the right. All points are the averages of at least five oocytes (± SEM).