Muscle RelaxationRelaxationRelaxation TherapyDopamine AgonistsVasodilationDose-Response Relationship, DrugAcetylcholineMuscle ContractionGABA AgonistsNitric OxideMuscle, SmoothVasodilator AgentsEndothelium, VascularPurinergic P1 Receptor AgonistsAdrenergic beta-AgonistsMuscarinic AgonistsNitroarginineMuscle, Smooth, VascularBiological FactorsRats, Sprague-DawleyNitroprussideNicotinic AgonistsAdrenergic AgonistsAdrenergic alpha-2 Receptor AgonistsCalciumIsoproterenolHistamine AgonistsSerotonin 5-HT2 Receptor AgonistsAorta, ThoracicRats, WistarPhenylephrineMesenteric ArteriesPurinergic P2 Receptor AgonistsSerotonin 5-HT1 Receptor AgonistsGuinea PigsMagnetic Resonance SpectroscopyAdrenergic alpha-AgonistsCholinergic AgonistsElectric StimulationCyclic GMPNG-Nitroarginine Methyl EsterGABA-A Receptor AgonistsMyocardial ContractionGastric Fundus15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidAdrenergic beta-3 Receptor AgonistsOxadiazolesTracheaCarbacholBradykininRabbitsEnzyme InhibitorsQuinoxalinesIndomethacinVasoconstrictor AgentsNitric Oxide SynthaseAdenosine A1 Receptor AgonistsNorepinephrineCyclic AMPAdrenergic alpha-1 Receptor AgonistsMethylene BlueArginineReceptors, Adrenergic, betaCharybdotoxinPotassium ChlorideTime FactorsCannabinoid Receptor AgonistsKineticsPenisExcitatory Amino Acid AgonistsAdenosineAortaDogsApaminReceptors, Opioid, muLigandsCells, CulturedDiastoleSerotoninRadioligand AssayReceptors, Opioid, kappaPiperidinesMuscle TonusCoronary VesselsAdenosine A3 Receptor AgonistsVasoactive Intestinal PeptideSerotonin AntagonistsArteriesSwineVasoconstrictionGuanylate CyclaseMembrane PotentialsReceptors, Adrenergic, beta-2Nitric Oxide DonorsEsophageal Sphincter, LowerGABA-B Receptor AgonistsSerotonin 5-HT4 Receptor AgonistsPhenoxyacetatesDrug InteractionsIndoles