Florescence polarization assay for PDE3A activity. Increasing concentrations of the PDE9 inhibitor, BAY 73-6691, were evaluated for inhibitory properties against PDE3A activity at 0 µM (no inhibitor), 1 µM, 10 µM, 100 µM, and 1 mM (Red). Similarly, the cGMP analog, 8-Br-cGMP, was assayed at 0 µM (no inhibitor), 1 µM, 10 µM, 100 µM, 1 mM and 10 mM (Blue). No significant changes were observed for the PDE9 inhibitor. Different letters indicate a significant decrease in PDE3A and Z’ = 0.75 for both assays. Significant changes in activity were analyzed by ANOVA followed by posthoc comparison with Student-Newman-Keuls test with P<0.001. Error bars indicate the first standard deviation.