TABLE 3

Parameters for interactions of indicated drugs with hα 2-nAChR in transfected SH-EP1 cells.

Results presented in Figs. 6, 7, 8, 9 and in Tables 1 and 2 are summarized. Functional EC₅₀ values for agonists, (column 2), functional IC₅₀ values for antagonists (column 3; functional IC₅₀ values given in parentheses for nicotine and suberyldicholine from fits to the self-inhibitory phase of agonist dose-response profiles for those drugs), and [³H]EBDN binding competition K_i values (column 4), all in micromolar, are expressed to allow comparisons between functional and radioligand binding competition affinities for the indicated ligands (drug; column 1). Also indicated (F/B; column 5) is the ratio between the functional EC₅₀/IC₅₀ and the binding competition K_i value (based on the IC₅₀ value but corrected for the concentration of H-EBDN used in those assays and for the H-EBDN binding K_d of 10 pM using the Cheng-Prusoff correction) for each ligand. The notations after the drug name for selected ligands indicate, from results shown in Fig. 9, functional antagonism actions as a noncompetitive inhibitor (N), a competitive inhibitor (C), or a mixed competitive/noncompetitive inhibitor (N/C).