Pharmacological characterization of recombinant bovine α3β4 neuronal nicotinic receptors stably expressed in HEK 293 cells

In these studies, [H-3]epibatidine is used as the radioligand to characterize recombinant bovine alpha(3)beta(4) nicotinic acetylcholine receptors (nAChRs) expressed in HEK 293 cells. Specific binding reaches equilibrium quickly and is saturable with a K-d value of 0.66 nM. The affinities of the several cholinergic agents were determined, including nicotine (K-i, 0.5 muM), cytisine (K-i, 0.5 muM), carbachol (K-i, 4.1 muM), dihydro-(beta)-erythroidine (K-i, 43.5 muM), d-tubocurarine (K-i, 0.1 muM), 1,1-dimethyl-4-phenylpiperazinium (K-i, 0.5 muM), decamethonium (K-i, 175 muM) and methyllycaconitine (K-i, 0.4 muM). These studies show that the pharmacological characteristics of recombinant bovine alpha(3)beta(4) nAChRs are similar to native bovine alpha(3)beta(4)* nAChRs, and indicate that the alpha5 subunit, if present in the native nAChRs, does not affect ligand affinity. (C) 2003 Published by Elsevier Science Ireland Ltd.