Phosphodiesterase InhibitorsRolipram4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinoneMilrinonePurinonesPyrrolidinones3',5'-Cyclic-AMP PhosphodiesterasesCyclic Nucleotide Phosphodiesterases, Type 4Phosphoric Diester HydrolasesPhosphodiesterase 3 InhibitorsPhosphodiesterase 4 Inhibitors3',5'-Cyclic-GMP Phosphodiesterases1-Methyl-3-isobutylxanthineCyclic Nucleotide Phosphodiesterases, Type 5Cyclic AMPSulfonesCyclic GMPCyclopropanesPyridazinesAminopyridinesPurinesTheophyllineCyclic Nucleotide Phosphodiesterases, Type 3Phosphodiesterase 5 InhibitorsPapaverinePiperazinesGuinea PigsDose-Response Relationship, DrugPyridinesPhosphodiesterase IBenzamidesCyclic Nucleotide Phosphodiesterases, Type 12',3'-Cyclic-Nucleotide PhosphodiesterasesColforsinPentoxifyllineBucladesineXanthines8-Bromo Cyclic Adenosine MonophosphateNucleotides, CyclicAdenylate CyclaseIsoproterenolEnoximoneVinca AlkaloidsAmrinoneAminophyllineBufo bufoCyclic AMP-Dependent Protein KinasesCyclic Nucleotide Phosphodiesterases, Type 2Photoreceptor CellsCyclic Nucleotide Phosphodiesterases, Type 6KineticsDibutyryl Cyclic GMPCalciumGuanylate CyclaseDipyridamoleErectile DysfunctionAlprostadilPhthalazinesPyridonesThionucleotidesAdenosinePhenylisopropyladenosineCyclic Nucleotide Phosphodiesterases, Type 7Enzyme ActivationCells, CulturedProstaglandins IPenile ErectionCyclic GMP-Dependent Protein KinasesSecond Messenger SystemsStimulation, ChemicalIsoquinolines