Basilar ArteryInfarction, Middle Cerebral ArteryMiddle Cerebral ArteryTomography, X-Ray ComputedCerebral ArteriesInfarction, Posterior Cerebral ArteryEpidermal CystBrain IschemiaPosterior Cerebral ArteryCerebrovascular CirculationCerebral InfarctionArteriesVertebrobasilar InsufficiencyCerebral AngiographyBrainMagnetic Resonance ImagingVertebral ArteryAcute DiseaseSubarachnoid HemorrhageIschemic Attack, TransientArterial Occlusive DiseasesCerebral Arterial DiseasesUltrasonography, Doppler, TranscranialCarotid ArteriesIntracranial AneurysmVasospasm, IntracranialIntracranial Embolism and ThrombosisBlood Flow VelocityPulmonary ArteryCarotid Artery, InternalBrain Stem InfarctionsMagnetic Resonance AngiographyVasodilationVasoconstrictionCerebral PalsyStrokeBrain EdemaMesenteric ArteriesCerebrovascular DisordersRenal ArteryFemoral ArteryEar, MiddleDisease Models, AnimalCerebral HemorrhageReperfusionAnterior Cerebral ArteryMuscle, Smooth, VascularRats, Sprague-DawleyNeuroprotective AgentsCircle of WillisCerebral VeinsTime FactorsAneurysm, RupturedBrain InfarctionCarotid Artery DiseasesVasodilator AgentsCerebral RevascularizationDogsUmbilical ArteriesTemporal ArteriesIntracranial ThrombosisAngiography, Digital SubtractionTreatment OutcomeRegional Blood FlowSerotoninCoronary Artery BypassIliac ArteryRadial ArteryIntracranial ArteriosclerosisBlood PressureMalaria, CerebralRats, WistarPapaverineMammary ArteriesVasoconstrictor AgentsThrombolytic TherapyPia MaterCarotid StenosisFibrinolytic AgentsTissue Plasminogen ActivatorEmbolization, TherapeuticEndothelium, VascularCarotid Artery, CommonNimodipineSubclavian ArteryNeurologic ExaminationVasomotor SystemInjections, Intra-ArterialPotassium ChlorideRabbitsConstrictionMuscle ContractionIntracranial EmbolismReperfusion InjuryDose-Response Relationship, DrugCarotid Artery, ExternalAcetylcholineUltrasonography, DopplerConstriction, PathologicRats, Inbred SHR