8-Br-cGMP, Rp-8-Br-PET-cGMPS, LY294002, rosiglitazone, and zaprinast were purchased from Sigma-Aldrich. 740 Y-P was supplied by R&D systems. LY294002, rosiglitazone, and zaprinast were dissolved in dimethyl sulfoxide (final concentration 0.2%). The other drugs were prepared using distilled water.