Characterization of human alpha4beta2 neuronal nicotinic receptors stably expressed in SH-EP1 cells

Neurochem Res. 2001 Jun;26(6):683-93. doi: 10.1023/a:1010995521851.


These studies characterized human alpha4beta2 neuronal nicotinic receptors stably expressed in a human epithelial cell line (SH-EP1). Receptors in transfected SH-EPI-halpha4beta2 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 microM, 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-halpha4beta2 cells expressed a single class of high affinity binding sites for [3H]cytisine with a Kd of 0.63 +/- 0.08 nM and a Bmax of 6,797 +/- 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-EPI-halpha4beta2 cells may be a good model system to study regulation of human alpha4beta2 receptors, the most abundant nicotinic receptor subtype in brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaloids / metabolism
  • Azocines
  • Binding Sites
  • Binding, Competitive
  • Calcium / metabolism
  • Cell Line
  • Fura-2
  • Humans
  • Intracellular Membranes / metabolism
  • Mecamylamine / pharmacology
  • Neurons / drug effects
  • Neurons / metabolism*
  • Nicotine / antagonists & inhibitors
  • Nicotine / pharmacology
  • Osmolar Concentration
  • Quinolizines
  • Receptors, Nicotinic / metabolism*
  • Time Factors
  • Up-Regulation


  • Alkaloids
  • Azocines
  • Quinolizines
  • Receptors, Nicotinic
  • nicotinic receptor alpha4beta2
  • cytisine
  • Mecamylamine
  • Nicotine
  • Calcium
  • Fura-2