Phosphodiesterase InhibitorsSulfonesPurinesPhosphodiesterase 5 Inhibitors3',5'-Cyclic-AMP PhosphodiesterasesPhosphoric Diester Hydrolases3',5'-Cyclic-GMP PhosphodiesterasesPiperazinesCyclic Nucleotide Phosphodiesterases, Type 5Phosphodiesterase 4 InhibitorsCyclic Nucleotide Phosphodiesterases, Type 4Phosphodiesterase 3 InhibitorsCyclic Nucleotide Phosphodiesterases, Type 3Phosphodiesterase IRolipramErectile DysfunctionCyclic GMPCyclic Nucleotide Phosphodiesterases, Type 11-Methyl-3-isobutylxanthine2',3'-Cyclic-Nucleotide PhosphodiesterasesVasodilator AgentsPurinonesCyclic AMPPenile ErectionCyclic Nucleotide Phosphodiesterases, Type 24-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinoneMilrinoneCyclic Nucleotide Phosphodiesterases, Type 6Hypertension, PulmonaryCarbolinesPapaverineCyclic Nucleotide Phosphodiesterases, Type 7TheophyllinePyrrolidinonesPenisTransducinTriazinesImpotence, VasculogenicRod Cell Outer SegmentKineticsCyclic GMP-Dependent Protein KinasesPhotoreceptor CellsPyrimidinonesGuanylate CyclaseDose-Response Relationship, DrugAdenylate CyclasePyrophosphatasesPulmonary ArteryAdministration, OralVinca AlkaloidsNucleotides, CyclicCalmodulinEnzyme ActivationNitric OxidePriapismCattleXanthinesIloprostColforsinIsoenzymesCyclic AMP-Dependent Protein KinasesAlprostadilPyridazinesIsoproterenolDouble-Blind MethodHypertrophy, Right VentricularBucladesineCalciumRetinal Rod Photoreceptor CellsCross-Over StudiesImidazolesAmrinoneGlycerylphosphorylcholineMolecular Sequence DataVascular ResistanceRana catesbeianaHemodynamicsRats, WistarNitric Oxide DonorsTime Factors8-Bromo Cyclic Adenosine MonophosphateTreatment OutcomePentoxifyllineAminophyllineAmino Acid SequenceEnzyme InhibitorsCyclopropanesHydrolysisNucleotidasesDrug SynergismThionucleotidesRats, Sprague-DawleyCells, CulturedBlood PressureCyclic IMPSignal TransductionDictyosteliumDrug InteractionsAminopyridinesClitoris