ColicMesenteric ArteriesMesenteric Artery, SuperiorRenal ColicMesenteric Artery, InferiorArteriesMesenteric Vascular OcclusionCeliac ArterySuperior Mesenteric Artery SyndromePulmonary ArteryRenal ArteryFecal ImpactionCerebral ArteriesVasodilationMuscle, Smooth, VascularCarotid ArteriesHorse DiseasesVasoconstrictionFemoral ArterySplanchnic CirculationBasilar ArteryMesenteric VeinsBiological FactorsVasoconstrictor AgentsVasodilator AgentsUreteral DiseasesIliac ArterySplenic ArteryEndothelium, VascularSimethiconeNorepinephrineVertebral ArteryCoronary Artery BypassHepatic ArteryPhenylephrineMyographyRadial ArteryMammary ArteriesRats, WistarTomography, X-Ray ComputedAcetylcholineStomatognathic DiseasesEquidaeCarotid Artery, InternalDuodenostomySubclavian ArteryHorsesRats, Inbred WKYRats, Sprague-DawleyMuscle RelaxationMuscle ContractionAngiographyCarotid Artery DiseasesTreatment OutcomeCoronary VesselsNitric OxideTime FactorsDose-Response Relationship, DrugBrachial ArteryBlood PressureSuperior ColliculiUrolithiasisVena Cava, Superior