Fig. 1. Glutamate release in spinal synaptosomes from normal rats evoked by 20 μm capsaicin alone (control) or in the presence of 1–1,000 nm adenosine or 10–1,000 nm R-PIA. Each symbol represents the mean ± SE of 12 observations. *P < 0.05, compared with control by one-way analysis of variance; & = P < 0.05 compared to no R-PIA.