ABSTRACT
The diversity in intracellular signalling downstream of adenosine receptors is dependent on the receptor subtype activated by adenosine. A1 and A2A are considered high affinity receptors while A2B and A3 are considered as low affinity receptors. Despite the apparent widespread distribution of A2B in every cell of every species, the receptor number and low affinity for adenosine and its analogue, makes it the least wellcharacterised adenosine receptor. A2B adenosine receptors are classically coupled to Gs protein and elevation of cAMP levels in target cells, although, A2B have also been known to couple to Gq and not just Gs proteins, and also to couple to Mitogen activated protein kinases (MAPK). In the present study, changes in intracellular calcium concentration ([Ca2+]i) and MAPK phosphorylation following subtype-specific and non-specific agonists and antagonists stimulation were investigated in human neuroblastoma SH-SY5Y cell line. In conclusion, our results indicate that SH-SY5Y cells express A2B adenosine receptors that are coupled to stimulation of Extracellular regulated kinase (ERK1/2) mitogen activated protein (MAP) kinases.