TABLE 4

Comparisons of functional EC50 or IC50 values for human α 4β2-nAChR expressed in different systems.

Functional EC50 values for agonists or functional IC50 values for antagonists (all in micromolar) are summarized for studies examining human α 4β2-nAChR heterologously expressed in human SH-EP1 or HEK cells or in oocytes and assessed using 86Rb+ efflux assays, membrane potential fluorescence (Vm fluor), or whole-cell current recording (e'phys) as indicated.

Drug This Study SH-EP1 86Rb+ efflux Buisson et al., 1996 HEK e'phys Gopalakrishnan et al., 1996 HEK 86Rb+ efflux Fitch et al., 2003 HEK Vm fluor Chavez Noriegaet al., 1997 Oocyte e'phys Papke et al., 2000 Oocyte e'phys
Epibatidine 0.0085 N.R. 0.017 0.0053 N.R. N.R.
Nicotine 0.85 1.6 4.0 0.86 5.5 52
Cytisine 1.3 12 38 1.7 2.6 N.R.
ACh 1.7 3.0 44 N.R. 68 92
DMPP 1.9 N.R. 2.5 2.2 18 N.R.
DHβEa 1.5 0.08b 1.9 25 0.11 N.R.
MLAa 6.6 1.5b N.R. N.R. N.R. N.R.
d-Tubocurarinea 62 N.R. N.R. N.R. 3.2 N.R.
  • N.R., not reported.

  • a Antagonists.

  • b Values indicated were obtained not from blockade of whole-cell peak currents but from blockade of steady-state currents after part of the whole-cell response had desensitized.