Basilar ArteryPonsCerebellumArteriesVertebrobasilar InsufficiencyVertebral ArteryCerebral ArteriesBrain Stem InfarctionsPulmonary ArteryCarotid ArteriesSubarachnoid HemorrhageCerebral AngiographyVasospasm, IntracranialMesenteric ArteriesRenal ArteryBrain StemFemoral ArteryBrainVasodilationPurkinje CellsVasoconstrictionCarotid Artery, InternalIntracranial AneurysmMuscle, Smooth, VascularCerebrovascular CirculationMagnetic Resonance ImagingCerebellar DiseasesIliac ArteryCoronary Artery BypassRadial ArteryArterial Occlusive DiseasesMammary ArteriesDogsVasodilator AgentsMagnetic Resonance AngiographySerotoninCarotid Artery DiseasesTomography, X-Ray ComputedSubclavian ArteryCerebellar CortexMiddle Cerebral ArteryPotassium ChlorideSplenic ArteryBrachial ArteryRabbitsPapaverineCircle of WillisCoronary VesselsMuscle ContractionCerebral InfarctionHepatic ArteryVasoconstrictor AgentsCarotid Artery, CommonPicolinesSumatriptanRats, Sprague-DawleyAcetylcholineEndothelium, VascularAngiography, Digital SubtractionTreatment OutcomeTime FactorsUltrasonography, Doppler, TranscranialIschemic Attack, TransientCeliac ArteryIntracranial ArteriosclerosisAneurysm, RupturedOphthalmic ArteryMesenteric Artery, SuperiorEmbolization, TherapeuticIntracranial Embolism and ThrombosisAngiographyUmbilical ArteriesRenal Artery ObstructionThoracic ArteriesVasomotor SystemDose-Response Relationship, DrugCerebellar AtaxiaTemporal ArteriesRegional Blood FlowBronchial ArteriesNitroprussidePosterior Cerebral ArteryPopliteal ArteryMuscle RelaxationDisease Models, AnimalUlnar ArteryNitroglycerinSubclavian Steal SyndromeCerebellar NucleiStentsNorepinephrineBrain IschemiaCerebrovascular DisordersInfusions, Intra-ArterialUterine ArteryThrombolytic TherapyImage Processing, Computer-AssistedNeuronsSpasmConstriction, Pathologic