BradycardiaAtropineHeart RateParasympatholyticsVagus NerveMuscarinic AntagonistsAtropine DerivativesApneaHypotensionParasympathetic Nervous SystemReflexBlood PressureVagotomyReceptors, MuscarinicSinoatrial NodeReflex, OculocardiacHexamethonium CompoundsArrhythmia, SinusAcetylcholineElectrocardiographyHeart BlockElectric StimulationBiguanidesAutonomic Nervous SystemPropranololCarbacholGlycopyrrolatePralidoxime CompoundsPhysostigmineBaroreflexDivingParasympathomimeticsAnesthesiaSick Sinus SyndromeAutonomic AgentsPirenzepineRespirationPacemaker, ArtificialSyncopeMethacholine CompoundsHeartCardiovascular SystemDogsSympatholyticsNeostigmineGuinea PigsTachycardiaMydriaticsMuscle, SmoothClonidinePressoreceptorsMuscarinic AgonistsSympathetic Nervous SystemGuanethidineArrhythmias, CardiacPhentolamineDecerebrate StateAtrioventricular BlockChemoreceptor CellsMedulla OblongataSyncope, VasovagalDose-Response Relationship, DrugOrganophosphate PoisoningSympathomimeticsMuscle ContractionAnti-Arrhythmia AgentsPreanesthetic MedicationCardiac Pacing, ArtificialCarotid SinusImmersionCholinesterase InhibitorsCatsGanglionic BlockersReceptor, Muscarinic M2HemodynamicsAdrenergic beta-AntagonistsRats, WistarMicroinjectionsConsciousnessNeurons, EfferentDenervationAdjuvants, AnesthesiaDepression, ChemicalTime FactorsHeart ArrestNorepinephrineAtenololCiguatera PoisoningCholinesterase ReactivatorsPostsynaptic Potential SummationSolitary NucleusCardiovascular Physiological PhenomenaHeart AtriaPhenylephrineInjections, IntravenousTorsades de PointesRats, Sprague-DawleyIntraoperative ComplicationsTilt-Table TestInjections, Intraventricular