Identification of alpha 2-adrenergic receptor sites in human retinoblastoma (Y-79) and neuroblastoma (SH-SY5Y) cells

Biochem Biophys Res Commun. 1989 Feb 15;158(3):921-8. doi: 10.1016/0006-291x(89)92810-6.

Abstract

The existence of specific alpha 2-adrenergic receptor sites has been shown in human retinoblastoma (Y-79) and neuroblastoma (SH-SH5Y) cells using direct radioligand binding. [3H]Rauwolscine, a selective alpha 2-adrenergic receptor antagonist, exhibited high affinity, saturable binding to both Y-79 and SH-SY5Y cell membranes. The binding of alpha 1 specific antagonist, [3H]Prazocine, was not detectable in either cell type. Competition studies with antagonists yielded pharmacological characteristics typical of alpha 2-adrenergic receptors: rauwolscine greater than yohimbine greater than phentolamine greater than prazocine. Based on the affinity constants of prazocine and oxymetazoline, it appears that Y-79 cells contain alpha 2A receptor, whereas SH-SY5Y cells probably represent a mixture of alpha 2A and alpha 2B receptors. alpha 2-agonists clonidine and (-)epinephrine inhibition curves yielded high and low affinity states of the receptor in SH-SY5Y cells. Gpp(NH)p and sodium ions reduced the proportion of high affinity sites of alpha 2 receptors. These two neuronal cell lines of human origin would prove useful in elucidating the action and regulation of human alpha 2-adrenergic receptors and their interaction with other receptor systems.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding, Competitive
  • Cell Membrane / metabolism
  • Clonidine / pharmacology
  • Epinephrine / pharmacology
  • Guanylyl Imidodiphosphate / pharmacology
  • Humans
  • Neuroblastoma / metabolism*
  • Phentolamine / metabolism
  • Prazosin / metabolism
  • Receptors, Adrenergic, alpha / drug effects
  • Receptors, Adrenergic, alpha / metabolism*
  • Retinoblastoma / metabolism*
  • Sodium / pharmacology
  • Tritium
  • Tumor Cells, Cultured
  • Yohimbine / metabolism

Substances

  • Receptors, Adrenergic, alpha
  • Tritium
  • Yohimbine
  • Guanylyl Imidodiphosphate
  • Sodium
  • Clonidine
  • Prazosin
  • Epinephrine
  • Phentolamine