Characterization Of Human Î±4Î²2 Neuronal Nicotinic Receptors Stably Expressed In Sh-Ep1 Cells
These studies characterized human Î±4Î²2 neuronal nicotinic receptors stably expressed in a human epithelial cell line (SH-EP1). Receptors in transfected SH-EP1-hÎ±4Î²2 cells were functional, as determined by increases in intracellular Ca2+in response to a nicotine stimulus. Nicotine increased Fura-2 fluorescence in a concentration-dependent manner with an apparent EC50 of 2.4 Î¼M, a response that was blocked by the specific antagonist mecamylamine. When cells were incubated in 50 nM nicotine for 24 hours, the Ca2+ response inactivated by 44%, an effect that recovered within 24 hours. SH-EP1-hÎ±4Î²2 cells expressed a single class of high affinity binding sites for [3H]cytisine with a Kd of 0.63 Â± 0.08 nM and a Bmax of 6797 Â± 732 femtomoles/mg protein. Incubation of cells with 50 nM nicotine for 24 hours increased the Bmax by 45% without changing affinity, a concentration-dependent effect with an EC50 of 58.6 nM. The nicotine-induced up regulation was reversible, and control values were achieved within 24 hours. Results indicate that SH-EP1-hÎ±4Î²2 cells may be a good model system to study regulation of human Î±4Î²2 receptors, the most abundant nicotinic receptor subtype in brain.
Digital Object Identifier (DOI)
Pacheco, Mary A.; Pastoor, Tina E.; Lukas, Ronald J.; and Wecker, Lynn, "Characterization Of Human Î±4Î²2 Neuronal Nicotinic Receptors Stably Expressed In Sh-Ep1 Cells" (2001). Neurobiology. 192.