Basilar ArteryInfarction, Posterior Cerebral ArteryTomography, X-Ray ComputedEpidermal CystPosterior Cerebral ArteryArteriesVertebrobasilar InsufficiencyInfarction, Middle Cerebral ArteryVertebral ArteryCerebral ArteriesBrain IschemiaAcute DiseaseMagnetic Resonance ImagingPulmonary ArteryCarotid ArteriesSubarachnoid HemorrhageBrain Stem InfarctionsCerebral AngiographyVasospasm, IntracranialMesenteric ArteriesRenal ArteryFemoral ArteryBrainVasodilationVasoconstrictionCarotid Artery, InternalIntracranial AneurysmMuscle, Smooth, VascularIliac ArteryCoronary Artery BypassRadial ArteryArterial Occlusive DiseasesMammary ArteriesVasodilator AgentsMagnetic Resonance AngiographyDogsCarotid Artery DiseasesSerotoninSubclavian ArteryCerebrovascular CirculationMiddle Cerebral ArterySplenic ArteryBrachial ArteryPotassium ChloridePapaverineCircle of WillisCoronary VesselsMuscle ContractionHepatic ArteryVasoconstrictor AgentsCarotid Artery, CommonPicolinesSumatriptanRabbitsAcetylcholineEndothelium, VascularAngiography, Digital SubtractionUltrasonography, Doppler, TranscranialCeliac ArteryIschemic Attack, TransientIntracranial ArteriosclerosisAneurysm, RupturedOphthalmic ArteryMesenteric Artery, SuperiorTreatment OutcomeEmbolization, TherapeuticIntracranial Embolism and ThrombosisAngiographyPonsUmbilical ArteriesRenal Artery ObstructionThoracic ArteriesVasomotor SystemTemporal ArteriesCerebral InfarctionBronchial ArteriesNitroprussidePopliteal ArteryMuscle RelaxationUlnar ArteryNitroglycerinSubclavian Steal SyndromeDose-Response Relationship, DrugStentsInfusions, Intra-ArterialUterine ArteryThrombolytic TherapyBrain StemSpasmConstriction, PathologicIntracranial ThrombosisRegional Blood FlowCoronary AngiographyInjections, Intra-ArterialComaCarotid Artery, ExternalTime Factors15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidNimodipineCarotid Stenosis