Figure 5. Adenosine acting via A_2A receptors mediates crosstalk from type II to type I cells .

In A and B, the UTP‐evoked delayed responses in ‘follower’ type I cells are almost completely inhibited by the selective adenosine A_2A receptor blocker SCH 58261 (5 nm) and the effect is reversible (***P < 0.001); notably SCH 58261 had no significant effect on the UTP‐evoked responses in ‘driver’ type II cells. By contrast, the selective adenosine A_2B blocker MRS 1754 (100 nm) had little or no effect in comparable experiments (C and D). A histogram of the percentage of type I cells sensitive to the A_2A and A_2B receptor blockers versus percentage inhibition of intracellular Ca²⁺ rise is shown in E (n = number of dishes sampled; 5–20 cells sampled per dish).