TABLE 3

Analyses of ligand competition binding studies in the rat retina The Ki values, Hill slope, and fraction of sites were derived from nonlinear, least square analyses using Prism software applied to competition binding curves, as shown in Fig. 3. The concentration of [3H]EB used in these studies was 500 pM. The binding of all ligands fit best to a two-site model, with the larger fraction representing the higher-affinity site. In all cases, a one-sample t test indicated that the Hill slopes were <1 (p < 0.01). Data are the mean ± S.E.M. of three to four independent experiments.

Ligand Ki(1) Ki(2) Hill Slope Fraction of Ki(1) N
nM nM
A-85380 0.22 ± 0.02 105 ± 17 0.71 ± 0.04 0.81 ± 0.01 4
HFI-55 0.89 ± 0.2 4348 ± 595 0.48 ± 0.02 0.84 ± 0.001 4
Cytisine 1.8 ± 0.4 398 ± 123 0.63 ± 0.04 0.67 ± 0.04 4
Nicotine 8.6 ± 1 593 ± 107 0.80 ± 0.02 0.72 ± 0.04 4
Dihydro-β-erythroidine 162 ± 55 36,000 ± 6,000 0.65 ± 0.04 0.75 ± 0.02 3