VasodilationVasodilator AgentsForearmNitric OxideEndothelium, VascularNitroprussideArteriolesRegional Blood FlowAcetylcholineMild Cognitive ImpairmentCognition DisordersBrachial ArteryVascular Resistanceomega-N-MethylarginineHyperemiaNitroglycerinNitric Oxide SynthaseCoronary CirculationCoronary VesselsVasoconstrictionNG-Nitroarginine Methyl EsterBlood PressureBlood Flow VelocityMicrocirculationLaser-Doppler FlowmetryVasomotor SystemHemodynamicsAdenosineEnzyme InhibitorsDose-Response Relationship, DrugEndothelium-Dependent Relaxing FactorsNeuropsychological TestsMesenteric ArteriesNitric Oxide Synthase Type IIIDogsBradykininRats, Sprague-DawleyNitroarginineVasoconstrictor AgentsPlethysmographyIndomethacinPia MaterMemory DisordersBiological FactorsArginineSkinCyclooxygenase InhibitorsInfusions, Intra-ArterialAnalysis of VarianceTime FactorsPulmonary CirculationHeart RateNitric Oxide DonorsBretylium TosylateMuscle, Smooth, VascularArteriesAgingRats, WistarCerebrovascular CirculationPapaverineAnoxiaCerebral ArteriesPotassium Channel BlockersSweatingSkin TemperatureReference ValuesDisease Models, AnimalRenal CirculationMyographyGlyburideBody Temperature RegulationPotassium ChannelsVision DisordersBrainHypertensionCalcitonin Gene-Related PeptideMuscle, SkeletalAlzheimer DiseaseIsosorbide DinitrateCyclic GMPSwineProstaglandins15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidVisually Impaired PersonsBlood VesselsAmnesiaPhenylephrineNorepinephrineOxygen ConsumptionFlushingDementiaPurinergic P1 Receptor AntagonistsGuanylate CyclaseCognitionOxygenMemoryPulmonary ArteryNitritesSeverity of Illness IndexPotassium Chloride