Involvement of NO in adenosine-induced depression.A, Changes in EPP amplitude expressed as a percentage of control amplitude before, during, and after bath perfusion with adenosine (10 μm; Ado; horizontal bar) after an application of SNAP (50 μm) for 30 min. The gray horizontal bar represents the mean ± 1 SEM obtained when adenosine was applied alone, with no previous treatment. Similar results were obtained in six experiments.B, Changes in EPP amplitude expressed as a percentage of control amplitude before, during, and after bath perfusion of adenosine (10 μm; Ado; horizontal bar) together with LY-83583 (40 μm) after an application of LY-83583 for 30 min. The gray horizontal bar represents the mean ± 1 SEM obtained when adenosine was applied alone, with no previous treatment. C, Histogram showing the average of adenosine-induced depression expressed as a percentage of control EPP amplitude and obtained in the three conditions tested. The amount of adenosine (Ado) depression was significantly reduced when the NO-dependent mechanisms were activated (Ado after SNAP) or when the cGMP-dependent cascade was blocked (Ado with LY-83583) (*p < 0.05, ANOVA test).