Regional Blood FlowBlood Flow VelocityCerebrovascular CirculationLaser-Doppler FlowmetryFlow CytometryBlood PressureVascular ResistancePulsatile FlowReproducibility of ResultsXenon RadioisotopesHemodynamicsMicrospheresTime FactorsDogsOxygenOxygen ConsumptionMicrocirculationRheologyCarbon DioxideTomography, Emission-ComputedBrainRenal CirculationVasodilationPulmonary CirculationLiver CirculationHeart RateUltrasonography, DopplerOxygen RadioisotopesReference ValuesHyperemiaSplanchnic CirculationBlood VolumeXenonPlethysmographyUltrasonography, Doppler, ColorSensitivity and SpecificityBlood Circulation TimeArteriesModels, CardiovascularVasodilator AgentsGene FlowCerebral ArteriesCollateral CirculationPartial PressureImage Processing, Computer-AssistedMagnetic Resonance ImagingVasoconstrictionNitric OxideBlood Gas AnalysisCapillariesLegMuscle, SkeletalUltrasonography, Doppler, TranscranialAnalysis of VarianceHindlimbIschemiaProspective StudiesSwineRats, Sprague-DawleyPregnancyModels, BiologicalEquipment DesignRetinal VesselsPerfusionPressureObserver VariationUltrasonographySkinMiddle Cerebral ArterySheepSkin TemperatureAntipyrineChoroidFemoral ArteryTomography, Emission-Computed, Single-PhotonAlgorithmsKidneyHeartNitrogen RadioisotopesBrain IschemiaStress, MechanicalDisease Models, AnimalDose-Response Relationship, DrugVasomotor SystemCoronary CirculationImaging, Three-DimensionalRetinal ArteryCalibrationRabbitsPhysical ExertionUltrasonography, Doppler, PulsedUltrasonography, PrenatalOximesHematocritHomeostasisEndothelium, VascularArteriolesKryptonTechnetium Tc 99m ExametazimePredictive Value of Tests