Basilar ArteryArteriesVertebrobasilar InsufficiencyMorbidityVertebral ArteryCerebral ArteriesPulmonary ArteryCarotid ArteriesSubarachnoid HemorrhageBrain Stem InfarctionsCerebral AngiographyVasospasm, IntracranialMesenteric ArteriesFemoral ArteryRenal ArteryVasodilationVasoconstrictionCarotid Artery, InternalIntracranial AneurysmMuscle, Smooth, VascularCoronary Artery BypassIliac ArteryArterial Occlusive DiseasesRadial ArteryMammary ArteriesVasodilator AgentsMagnetic Resonance AngiographyDogsCarotid Artery DiseasesSubclavian ArteryCerebrovascular CirculationSerotoninTreatment OutcomeTomography, X-Ray ComputedMiddle Cerebral ArteryBrachial ArterySplenic ArteryPotassium ChlorideCoronary VesselsPapaverineCircle of WillisHepatic ArteryMuscle ContractionCarotid Artery, CommonVasoconstrictor AgentsPicolinesRabbitsSumatriptanEndothelium, VascularAngiography, Digital SubtractionAneurysm, RupturedAcetylcholineEmbolization, TherapeuticCeliac ArteryUltrasonography, Doppler, TranscranialIschemic Attack, TransientIntracranial ArteriosclerosisMesenteric Artery, SuperiorOphthalmic ArteryAngiographyTime FactorsIntracranial Embolism and ThrombosisUmbilical ArteriesPonsRetrospective StudiesRenal Artery ObstructionThoracic ArteriesVasomotor SystemCerebral InfarctionFollow-Up StudiesTemporal ArteriesStentsBronchial ArteriesPopliteal ArteryNitroprussideDose-Response Relationship, DrugPosterior Cerebral ArteryUlnar ArteryMuscle RelaxationRisk FactorsNitroglycerinSubclavian Steal SyndromeProspective StudiesConstriction, PathologicInfusions, Intra-ArterialThrombolytic TherapyUterine ArteryBrain StemRegional Blood FlowIntracranial ThrombosisSpasmCoronary AngiographyInjections, Intra-ArterialComaCarotid Artery, ExternalCarotid StenosisCerebrovascular DisordersRats, Sprague-DawleyAneurysmNimodipine