Penile ErectionPenisPriapismErectile DysfunctionArteriesImpotence, VasculogenicYawningPhosphodiesterase 5 InhibitorsNepetaSulfonesApomorphinePurinesEjaculationPapaverinePiperazinesAlprostadilNitric Oxide Synthase Type ICopulationPulmonary ArterySulpiridePhosphodiesterase InhibitorsNitric OxideCyclic Nucleotide Phosphodiesterases, Type 5Carotid ArteriesCerebral ArteriesRenal ArteryFemoral ArteryMesenteric ArteriesNitric Oxide SynthaseElectric StimulationPenile IndurationDopamine AgonistsOrgasmPindololLibidoScopolamine HydrobromideMuscle, SmoothRats, Sprague-DawleyBasilar ArteryNG-Nitroarginine Methyl EsterVasodilator AgentsPressureMuscle RelaxationAdrenergic alpha-AntagonistsIliac ArteryVertebral ArteryCoronary Artery Bypass