Figure 2.

Removing extracellular adenosine, blocking ATP‐derived formation of extracellular adenosine, or antagonizing A_2A receptors (A_2AR) are equi‐effective in attenuating the dysfunction and damage in differentiated SY5Y neuroblastoma cells exposed to 6‐hydroxydopamine (6‐OHDA). Dopamine‐differentiated SY5Y cells were incubated for 24 hr in the absence or presence of 6‐OHDA (30 μM) without or with either adenosine deaminase (ADA, 2 U·ml⁻¹, which converts adenosine into inosine) or α,β‐methylene ADP (AOPCP, 100 μM, which inhibits the extracellular formation of adenosine from adenine nucleotides) or SCH58261 (100 nM, a selective antagonist of A_2A receptors) to measure either cellular dysfunction (assessed by a decrease of the reduction activity of cells using the colorimetric indicator MTT) in (a) or cellular damage (assessed by the release of the cytosolic enzyme, LDH) in (b). The data shown are means ± SEM of n = 3–6 in (a) and n = 4–8 in (b). **P < .05, significantly different from control; *P < .05, significantly different from 6‐OHDA; two‐tailed unpaired Student's t test