Liquid chromatographic studies with immobilized neuronal nicotinic acetylcholine receptor stationary phases: effects of receptor subtypes, pH and ionic strength on drug-receptor interactions.

Nicotinic acetylcholine receptor (nAChR) alpha3-subunits, beta4-subunits, alpha3/beta4-subunit combination and alpha4/beta2-subunit combination were immobilized on chromatographic stationary phases and the binding affinities of the different nAChR subtypes were chromatographically evaluated. The observed relative binding affinities of epibatidine were alpha4/beta2>alpha3/beta4 and epibatidine did not bind at alpha3-subunits and beta4-subunits. No significant difference in binding affinities was observed on the alpha4/beta2 nAChRs immobilized in immobilized artificial membrane (IAM) particles and those sterically immobilized on Superdex 200 beads. The effects of mobile phase pH and ionic strength on the binding affinities of the alpha3/beta4 nAChRs support were also investigated. The results are consistent with the proposed ligand-nAChR binding model in which a cationic center exists at the binding site.