Basilar ArteryPonsArteriesVertebrobasilar InsufficiencyVertebral ArteryCerebral ArteriesBrain Stem InfarctionsPulmonary ArterySubarachnoid HemorrhageCarotid ArteriesCerebral AngiographyVasospasm, IntracranialMesenteric ArteriesRenal ArteryFemoral ArteryVasodilationCranial Fossa, PosteriorIntracranial AneurysmCarotid Artery, InternalVasoconstrictionBrain StemPosterior Cerebral ArteryMagnetic Resonance ImagingMuscle, Smooth, VascularIliac ArteryCoronary Artery BypassTomography, X-Ray ComputedCerebrovascular CirculationArterial Occlusive DiseasesMagnetic Resonance AngiographyRadial ArteryMammary ArteriesDogsVasodilator AgentsCarotid Artery DiseasesSerotoninSubclavian ArteryCircle of WillisMiddle Cerebral ArteryBrainTreatment OutcomeBrachial ArterySplenic ArteryPotassium ChlorideCoronary VesselsCerebral InfarctionMuscle ContractionPapaverineRabbitsHepatic ArteryVasoconstrictor AgentsCarotid Artery, CommonPicolinesAngiography, Digital SubtractionAneurysm, RupturedSumatriptanUltrasonography, Doppler, TranscranialAcetylcholineEndothelium, VascularOphthalmic ArteryEmbolization, TherapeuticIntracranial ArteriosclerosisIschemic Attack, TransientCeliac ArteryTime FactorsAngiographyIntracranial Embolism and ThrombosisMesenteric Artery, SuperiorCerebellumUmbilical ArteriesThoracic ArteriesRenal Artery ObstructionRats, Sprague-DawleyFollow-Up StudiesVasomotor SystemTemporal ArteriesPopliteal ArteryRetrospective StudiesRegional Blood FlowPosterior Cruciate LigamentBronchial ArteriesDose-Response Relationship, DrugMuscle RelaxationNitroprussideInfarction, Posterior Cerebral ArteryUlnar ArteryStentsNitroglycerinSubclavian Steal SyndromeSpasmConstriction, PathologicCerebrovascular DisordersInfusions, Intra-ArterialBrain IschemiaThrombolytic TherapyImage Processing, Computer-AssistedNorepinephrineUterine ArteryIntracranial ThrombosisInjections, Intra-Arterial