Fig. 8.

Zn²⁺ increases the response of neuronal nAChRs to saturating ACh concentrations. ACh concentration–response relationships of α4β4- and α4β2-expressing oocytes in the absence (filled symbols) and presence (open symbols) of 50 μm Zn²⁺ are plotted as a percentage of the fit maximum response to ACh alone (mean ± SEM of 3 oocytes).A, Zn²⁺ (50 μm) significantly decreased the EC₅₀ of α4β4 receptors for ACh from 74 ± 22 to 23 ± 8 μm(p < 0.05) and significantly increased the maximal response to 160 ± 11% of the maximal response to ACh alone (p < 0.02). B, Zn²⁺ (50 μm) significantly increased the maximal response of α4β2 receptors to ACh to 140 ± 14% of the maximal response to ACh alone (p < 0.02).