NitroglycerinVasodilator AgentsDrug ToleranceAdministration, CutaneousVasodilationAdministration, SublingualNicorandilCoronary VesselsPentaerythritol TetranitrateDogsAldehyde DehydrogenaseTilt-Table TestSpasmBlood PressureAngina PectorisPeripheral Nervous System AgentsCoronary CirculationOintmentsFerricyanidesVascular ResistanceNitric OxideHemodynamicsHeart RateBrachial ArteryCoronary VasospasmAcetylcholineEndothelium, VascularNitric Oxide DonorsIsosorbide DinitrateDiltiazemNitratesCyclic GMPSyncope, VasovagalNitroprussidePapaverineMuscle RelaxationGuanylate CyclaseMethylene BlueInjections, Intra-ArterialRegional Blood FlowInfusions, IntravenousDouble-Blind MethodScorpion StingsCoronary DiseaseFissure in AnoCyanamideRadial ArteryHydralazineBlood Flow VelocityCoronary AngiographyVasoconstrictionS-NitrosothiolsAortaMuscle, Smooth, Vascular