Agonist Efficacy and Sensitivity for Activation and Desensitization.

The EC50’s for activation of α4β2, α3β4 and α7 AChRs are expressed in µM. In cases where the dose response curves fit with a two-site competition model, the EC50 for the higher sensitivity component is listed first. For desensitization, cell lines expressing various human AChRs were incubated overnight in the presence of a range of concentrations of agonists, and then tested for activation by ACh. For α4β2 AChRs, two concentrations of ACh were tested, namely 3 µM (to test the more sensitive stoichiometry (α4β2)2β2), and 100 µM ACh (to assay function of both stoichiometries). For the other AChRs, saturating concentrations of ACh were used (1.0 mM for α3β4 and 10 µM for α7).