HeartMyocytes, CardiacMyocardiumCardiac OutputMyocardial ContractionArrhythmias, CardiacCardiomegalyHeart RateVentricular RemodelingHeart VentriclesVentricular Function, LeftHeart Function TestsHemodynamicsBlood PressureHeart FailureElectrocardiographyEchocardiographyCardiotonic AgentsFibrosisVentricular FunctionCardiac Surgical ProceduresMyocardial InfarctionRats, Sprague-DawleyDeath, Sudden, CardiacStroke VolumeCardiomyopathy, DilatedCardiomyopathiesDogsTime FactorsIsoproterenolMyocardial IschemiaHeart Conduction SystemAdrenergic beta-AntagonistsOrgan SizeVentricular Dysfunction, LeftRats, WistarDisease Models, AnimalHeart DiseasesGuinea PigsDose-Response Relationship, DrugCalciumPapillary MusclesHeart AtriaHypertrophy, Left VentricularCardiac Pacing, ArtificialAngiotensin-Converting Enzyme InhibitorsParasympathetic Nervous SystemMyocardial Reperfusion InjuryVagus NerveAnti-Arrhythmia AgentsAtrial Natriuretic FactorCells, CulturedAngiotensin IIRabbitsCardiac TamponadeCardiac CatheterizationCoronary VesselsPhysical Conditioning, AnimalCoronary CirculationAction PotentialsNorepinephrinePropranololPhenylephrineReceptors, Adrenergic, betaHeart ArrestMice, TransgenicVascular ResistanceRandom AllocationAtropineCalcium Channels, L-TypeRNA, MessengerTreatment OutcomeSignal TransductionPerfusionSympathetic Nervous SystemCardiac MyosinsOxygen ConsumptionAnimals, NewbornCardiac ElectrophysiologyTroponin IBody WeightMice, Inbred C57BLCardiac Output, LowHypertensionCardiac GlycosidesAnalysis of VarianceMyoblasts, CardiacHeart TransplantationCardiac VolumeBlotting, WesternMice, KnockoutCardiac Imaging TechniquesEnergy MetabolismElectrophysiologyGene ExpressionPatch-Clamp TechniquesTroponin TOut-of-Hospital Cardiac ArrestPhosphorylationVentricular Pressure