Myocytes, CardiacAnimals, NewbornMyocardiumCells, CulturedCardiomegalyRats, Sprague-DawleyHeartHeart VentriclesRats, WistarMyocardial ContractionSignal TransductionGene Expression RegulationPhosphorylationCardiac Surgical ProceduresMitochondria, HeartCell SizeHeart Defects, CongenitalPhenylephrineCalciumRNA, MessengerMuscle CellsCardiac OutputArrhythmias, CardiacCalcium Channels, L-TypeFibroblastsIsoproterenolVentricular FunctionSodium-Calcium ExchangerSarcolemmaPatch-Clamp TechniquesCalcium SignalingGuinea PigsSarcomeresDeath, Sudden, CardiacSarcoplasmic ReticulumHeart AtriaAdrenergic beta-AgonistsInfant, NewbornMembrane PotentialsAction PotentialsCardiomyopathiesTime FactorsModels, CardiovascularReceptors, Adrenergic, betaHeart FailurePotassium ChannelsHeart DiseasesSarcoplasmic Reticulum Calcium-Transporting ATPasesCardiac Pacing, ArtificialCardiotonic AgentsMuscle ProteinsRyanodine Receptor Calcium Release ChannelAtrial Natriuretic FactorCalcium ChannelsGATA4 Transcription FactorRabbitsDogsMyocardial IschemiaElectrophysiologyCaveolin 3Receptors, Adrenergic, beta-1Troponin ICardiac TamponadeCardiac MyosinsMyosin Heavy ChainsMyocardial Reperfusion InjuryMyoblasts, CardiacEndothelin-1CaffeineMice, TransgenicVentricular RemodelingMyocardial InfarctionCardiomyopathy, DilatedCardiac CatheterizationMicroscopy, ConfocalSodium ChannelsEnzyme InhibitorsExcitation Contraction CouplingReceptors, Adrenergic, alpha-1Mice, KnockoutCyclic AMP-Dependent Protein KinasesMyocarditisMyofibrilsCardiac Output, LowHeart RateDose-Response Relationship, DrugElectrocardiographyProtein Kinase CHeart ArrestHypertrophyElectric ConductivitySodiumEchocardiographyDisease Models, AnimalCell SeparationHeart Conduction SystemAngiotensin IISodium-Potassium-Exchanging ATPaseVentricular Function, LeftPericardium