Penile ErectionPenisPriapismErectile DysfunctionImpotence, VasculogenicSulfonesPhosphodiesterase 5 InhibitorsYawningNepetaApomorphinePurinesEjaculationAlprostadilPapaverinePiperazinesPenile IndurationOrgasmLibidoCopulationNitric Oxide Synthase Type IPhosphodiesterase InhibitorsSulpirideCyclic Nucleotide Phosphodiesterases, Type 5Nitric OxideDopamine AgonistsElectric StimulationMuscle, SmoothScopolamine HydrobromidePindololNitric Oxide SynthasePressureNG-Nitroarginine Methyl EsterRats, Sprague-Dawley