Subtypes of alpha 1-adrenoceptors in DDT1 MF-2 and BC3H-1 clonal cell lines

Eur J Pharmacol. 1992 Jun 5;226(2):141-8. doi: 10.1016/0922-4106(92)90175-u.


We examined which subtype(s) of alpha 1-adrenoceptors are expressed in the widely used DDT1 MF-2 and BC3H-1 cell lines. Pretreatment with chloroethylclonidine (CEC) inactivated 76-85% of the specific [125I]BE 2254 binding sites in membrane preparations from both cell lines. Competition with subtype-selective competitive antagonists showed primarily the alpha 1B subtype in both cell lines. However, in BC3H-1 cells 5-methyl-urapidil showed complex behavior suggesting that about half of the binding sites had a lower affinity. Chloroethylclonidine pretreatment eliminated [3H]inositol phosphate responses to norepinephrine in both cell lines. Measurement of intracellular Ca2+ with fura-2 in DDT1 MF-2 cells showed that norepinephrine induced a complex response involving both transient and sustained components. Chloroethylclonidine pretreatment blocked both responses, while chelation of extracellular Ca2+ left the transient response intact but eliminated the sustained component. These results support previous work that these cell lines contain alpha 1B-adrenoceptors linked to inositol phosphate formation and mobilization of intracellular Ca2+. However, these results show that alpha 1B-adrenoceptors can be linked to Ca2+ influx as well as intracellular mobilization, and support the existence of pharmacologically distinct alpha 1B variants.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenergic alpha-Antagonists / metabolism
  • Binding, Competitive / drug effects
  • Calcium / metabolism
  • Cell Line
  • Clonidine / analogs & derivatives
  • Clonidine / pharmacology
  • Inositol Phosphates / metabolism
  • Muscle, Smooth / cytology
  • Muscle, Smooth / drug effects
  • Norepinephrine / metabolism
  • Phenethylamines / metabolism
  • Piperazines / metabolism
  • Radioligand Assay
  • Receptors, Adrenergic, alpha / drug effects
  • Receptors, Adrenergic, alpha / metabolism*
  • Tetralones*


  • Adrenergic alpha-Antagonists
  • Inositol Phosphates
  • Phenethylamines
  • Piperazines
  • Receptors, Adrenergic, alpha
  • Tetralones
  • 5-methylurapidil
  • chlorethylclonidine
  • BE 2254
  • Clonidine
  • Calcium
  • Norepinephrine