Basilar ArteryPonsArteriesVertebrobasilar InsufficiencyMesencephalonVertebral ArteryCerebral ArteriesBrain Stem InfarctionsPulmonary ArteryCarotid ArteriesSubarachnoid HemorrhageCerebral AngiographyVasospasm, IntracranialMesenteric ArteriesRenal ArteryFemoral ArteryBrain StemVasodilationVasoconstrictionCarotid Artery, InternalIntracranial AneurysmMuscle, Smooth, VascularIliac ArteryCoronary Artery BypassSerotoninCerebrovascular CirculationBrainRadial ArteryArterial Occlusive DiseasesMammary ArteriesVasodilator AgentsDogsMagnetic Resonance AngiographyCarotid Artery DiseasesMagnetic Resonance ImagingSubclavian ArteryTomography, X-Ray ComputedMiddle Cerebral ArterySplenic ArteryBrachial ArteryPotassium ChloridePapaverineCircle of WillisCoronary VesselsCerebral InfarctionMuscle ContractionHepatic ArteryVasoconstrictor AgentsCarotid Artery, CommonPicolinesRabbitsDopamineRats, Sprague-DawleyAcetylcholineSumatriptanEndothelium, VascularAngiography, Digital SubtractionUltrasonography, Doppler, TranscranialTreatment OutcomeCeliac ArteryCerebellumTime FactorsIschemic Attack, TransientDopaminergic NeuronsIntracranial ArteriosclerosisAneurysm, RupturedOphthalmic ArteryMesenteric Artery, SuperiorNeuronsEmbolization, TherapeuticIntracranial Embolism and ThrombosisAngiographyUmbilical ArteriesRenal Artery ObstructionDose-Response Relationship, DrugThoracic ArteriesVasomotor SystemTemporal ArteriesBronchial ArteriesNitroprussidePosterior Cerebral ArteryRegional Blood FlowPopliteal ArteryMuscle RelaxationUlnar ArteryNitroglycerinSubclavian Steal SyndromeNorepinephrineStentsInfusions, Intra-ArterialUterine ArteryDisease Models, AnimalThrombolytic TherapySpasmConstriction, PathologicPeriaqueductal GrayIntracranial ThrombosisCerebrovascular DisordersBrain IschemiaCoronary Angiography