Figure 3.

Concentration-response curves of the different adenosine receptor agonists (a) and antagonists (b) on the inhibitory descending reflex response. The reflex response was induced by electrical stimulation (EFS; 20 V, 2 ms, 3 pps, 15 s), and the response was recorded by contractility recording 2 cm aboral from the stimulation site (* = P < 0.05 for CPA/MRS 1191; + = P < 0.05 for CGS 21680/DPCPX; $ = P < 0.05 for IB-MECA/Alloxazine; § = P < 0.05 for ZM 341285).