Comparison of the Ca2+ movement by activation of alpha1-adrenoceptor subtypes in HEK-293 cells

Life Sci. 1997;61(21):2127-36. doi: 10.1016/s0024-3205(97)00886-2.


We studied the Ca2+ movement induced by activation of alpha1A-, alpha1B- and alpha1D-adrenoceptor subtypes in transfected HEK-293 cells with the fura-2 probe. All these alpha1-AR subtypes induced both Ca2+ release and Ca2+ entry. The effect on Ca2+ release in alpha1b transfected HEK-293 cells was bigger than that in alpha1a and alpha1d transfected HEK-293 cells, and the effects on Ca2+ entry were the same in alpha1a, alpha1b and alpha1d transfected HEK-293 cells. The Ca2+ entry was inhibited by 1 mM NiSO4, but not by nifedipine. Cyclopiazonic acid (CPA) produced a biphasic Ca2+ signal response in Ca2+ medium, and only induced a transient response in Ca2+-free medium. After depletion of CPA-sensitive Ca2+ pool by 10 microM CPA in Ca2+-free medium, 10 microM adrenaline (Adr) still transiently increased [Ca2+]i in three different alpha1-adrenoceptor subtype transfected HEK-293 cells. However, after depletion of adrenaline-sensitive Ca2+ pool by 10 microM Adr, CPA transiently elevated [Ca2+]i only in alpha1a and alpha1d transfected HEK-293 cells, not in alpha1b transfected HEK-293 cells. U73122, a phospholipase C (PLC) inhibitor, inhibited both Ca2+ release and Ca2+ entry induced by activation of alpha1A alpha1B and alpha1D subtypes in transfected HEK-293 cells. These results suggest that HEK-293 cell line contains two functionally separate intracellular Ca2+ pools, CPA-sensitive and Adr-sensitive pools. Activation of alpha1B-AR stimulates Ca2+ release from both CPA-sensitive and Adr-sensitive Ca2+ pools. Alpha1A and alpha1D subtypes induce Ca2+ release only from Adr-sensitive Ca2+ pool.

Publication types

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

MeSH terms

  • Animals
  • Caffeine / pharmacology
  • Calcium / metabolism*
  • Cattle
  • Cell Line
  • Cricetinae
  • Epinephrine / pharmacology
  • Humans
  • Indoles / pharmacology
  • Ion Transport
  • Potassium / pharmacology
  • Rats
  • Receptors, Adrenergic, alpha-1 / metabolism*
  • Ryanodine / pharmacology
  • Transfection
  • Type C Phospholipases / metabolism


  • Indoles
  • Receptors, Adrenergic, alpha-1
  • Ryanodine
  • Caffeine
  • Type C Phospholipases
  • Potassium
  • Calcium
  • cyclopiazonic acid
  • Epinephrine