Wakefulness-Promoting AgentsReceptors, Adrenergic, alpha-2VasoconstrictionVasoconstrictor AgentsReceptors, Adrenergic, alphaVascular ResistanceRegional Blood FlowPulmonary CirculationAnoxiaalpha 1-AntitrypsinAdrenergic alpha-AgonistsNorepinephrineAdrenergic alpha-AntagonistsBlood PressurePhenylephrinePulmonary ArteryArteriolesVasodilationEndothelin-1Receptors, Adrenergic, alpha-1Mesenteric ArteriesShiveringDose-Response Relationship, DrugRenal CirculationForearmSkin TemperatureMuscle, Smooth, VascularHypoxia-Inducible Factor 1, alpha SubunitHemodynamicsBody Temperature RegulationVasomotor SystemRats, Sprague-DawleyNitric OxidePrazosinVasodilator AgentsReceptors, Endothelin15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidSympathetic Nervous SystemAdrenergic alpha-1 Receptor AgonistsDogsPerfusionEndothelinsReceptor, Endothelin AArteriesMethoxamineNG-Nitroarginine Methyl Ester