Myocytes, CardiacMyocardiumHeartHeart VentriclesCardiac OutputMyocardial ContractionArrhythmias, CardiacCardiomegalyCardiac Surgical ProceduresMuscle CellsDeath, Sudden, CardiacCalciumVentricular FunctionCells, CulturedCalcium Channels, L-TypeCardiac Pacing, ArtificialHeart AtriaRats, Sprague-DawleyPatch-Clamp TechniquesSodium-Calcium ExchangerIsoproterenolGuinea PigsHeart DiseasesCardiac TamponadeAction PotentialsHeart FailureCardiomyopathiesAnimals, NewbornTime FactorsSarcolemmaCardiac CatheterizationCalcium SignalingPotassium ChannelsMembrane PotentialsCardiac MyosinsHeart ArrestAdrenergic beta-AgonistsSarcoplasmic ReticulumRats, WistarCardiotonic AgentsModels, CardiovascularMyoblasts, CardiacElectrocardiographyDogsSarcomeresMyocardial InfarctionCardiac Output, LowHeart RateCardiac GlycosidesVentricular RemodelingTroponin IElectrophysiologyCell SizeEchocardiographySarcoplasmic Reticulum Calcium-Transporting ATPasesRabbitsRyanodine Receptor Calcium Release ChannelCardiac Imaging TechniquesReceptors, Adrenergic, betaHemodynamicsVentricular Function, LeftMitochondria, HeartHeart Conduction SystemCalcium ChannelsMyocardial IschemiaCaffeineHeart TransplantationMuscle ProteinsCardiomyopathy, DilatedPericardiumAtrial Natriuretic FactorOut-of-Hospital Cardiac ArrestCardiac ElectrophysiologySodium ChannelsSignal TransductionCardiac VolumeExcitation Contraction CouplingDisease Models, AnimalMice, TransgenicEndocardiumAnti-Arrhythmia AgentsDose-Response Relationship, DrugRNA, MessengerElectric ConductivityTroponin TMyocardial Reperfusion InjuryHeart Defects, CongenitalBlood PressureHeart Function TestsVentricular Dysfunction, LeftFetal HeartMyosin Heavy ChainsSodiumFibrosisStroke VolumeHypertrophy, Left VentricularPotassium Channels, Voltage-GatedMice, KnockoutAtrial FunctionCalsequestrin