Figure 10.

Incubation in Nic increases the amount of α3β2 AChRs in IMR-32 and SH-SY5Y cells, but not α3β4 AChRs. The bar graph represents the relative amounts of [³H]epibatidine binding to AChRs immunoisolated on mAb-coated microwells from Triton-X100 extracts of either IMR-32 or SH-SY5Y cells in the presence and absence of Nic (100 μM) overnight. mAb 210 binds α3 and α5 AChRs, mAb 295 binds β2 AChRs, and mAb 337 binds β4 AChRs. For both cell lines, Nic caused an increase in binding to AChRs isolated on 210-coated wells which was the same in magnitude as the amount of increase in binding to AChRs isolated on mAb 295-coated wells. AChRs isolated on mAb 337-coated wells were not altered significantly by Nic. For IMR-32 (untreated), mAb 210 isolated AChRs bound ∼12 fmol of [³H]epibatidine, which corresponds to roughly 1,800 AChRs per cell when assuming two binding sites per AChR, whereas for SH-SY5Y, mAb 210 isolated AChRs bound ∼3 fmol of [³H]epibatidine corresponding to ∼600 AChRs per cell.