Effector coupling of stably transfected human A3 adenosine receptors in CHO cells

Biochem Pharmacol. 2002 Jul 1;64(1):61-5. doi: 10.1016/s0006-2952(02)01071-7.


CHO cells stably transfected with adenosine receptors are widely utilized models for binding and functional studies. The effector coupling of human A3 adenosine receptors expressed in such a cellular model was characterized. Inhibition of adenylyl cyclase via a pertussis toxin-sensitive G protein was confirmed and exhibited a pharmacological profile in accordance with agonist binding data. The agonist potency was dependent on the assay system utilized to measure cyclase inhibition. Agonists were more potent in a cell-based assay than in experiments where cyclase inhibition was measured in a membrane preparation suggesting that receptor-effector coupling might be more efficient in intact cells. In addition to the modulation of cyclase activity, stimulation of A3 receptors elicited a Ca2+ response in CHO cells with agonist potencies corresponding to the values for the whole cell cAMP assay. The Ca2+ signal was completely eliminated by pertussis toxin treatment suggesting that it is mediated via betagamma release from a heterotrimeric G protein of the Gi/o family. These results show that cAMP and Ca2+ signaling characteristics of the A3 adenosine receptor are comparable to the ones found for the A1 subtype.

MeSH terms

  • Animals
  • CHO Cells
  • Calcium Signaling / physiology*
  • Cricetinae
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Receptor, Adenosine A3
  • Receptors, Purinergic P1 / genetics
  • Receptors, Purinergic P1 / metabolism*
  • Transfection


  • Receptor, Adenosine A3
  • Receptors, Purinergic P1
  • GTP-Binding Proteins