NitroglycerinVasodilator AgentsDrug ToleranceAdministration, CutaneousVasodilationAdministration, SublingualNicorandilCoronary VesselsDogsPentaerythritol TetranitrateAldehyde DehydrogenaseTilt-Table TestSpasmBlood PressureAngina PectorisPeripheral Nervous System AgentsCoronary CirculationNitric OxideOintmentsCalciumFerricyanidesVascular ResistanceHemodynamicsHeart RateAcetylcholineEndothelium, VascularBrachial ArteryCoronary VasospasmNitric Oxide DonorsDiltiazemCyclic GMPIsosorbide DinitrateNitratesNitroprussideSyncope, VasovagalThapsigarginPapaverineMuscle RelaxationGuanylate CyclaseMethylene BlueRegional Blood FlowInfusions, IntravenousInjections, Intra-ArterialMuscle, Smooth, VascularDouble-Blind MethodDose-Response Relationship, DrugVasoconstrictionCoronary DiseaseScorpion StingsAortaFissure in AnoTime FactorsS-NitrosothiolsCyanamideBlood Flow VelocityRadial ArteryHydralazineCoronary AngiographyNifedipine