Table 1.

Affinity of nicotinic agonists and antagonists for immunoimmobilized nAChR subtypes

α6β2*α4(non α6)β2*
Kd (nm)
125I-Epibatidine0.034 (34)0.041 (25)
Ki (nm)
 Cytisine0.65 (18)0.19 (16)
 Nicotine2.5 (23)1.75 (23)
 Acetylcholine8.0 (34)8.6 (23)
 Dihydro-β-erythroidine524 (25)274 (21)
d-Tubocurarine3,110 (20)16,100 (28)
 α-Conotoxin MII1.3 (45)
 Methyllycaconitine40 (47)
20,800 (18)25,000 (23)
  • Kd and Ki values were derived from curves of 125I-Epi saturation and competition binding, respectively, to α6β2* or α4(nonα6)β2

  • * immunoimmobilized receptors. Curves obtained from three or four separate experiments were fitted using a nonlinear least-squares analysis program. For both α-conotoxin MII and methyllycaconitine, a two-site model was statistically significant (F test), whereas for d-tubocurarine and cytisine the data were better fitted with a one-site model. Numbers in parentheses represent percentage of coefficient of variation.