Myocytes, CardiacHeart VentriclesMyocardiumCells, CulturedMyocardial ContractionHeartRats, WistarCardiomegalyAnimals, NewbornCalciumVentricular FunctionCardiac MyosinsIsoproterenolCalcium Channels, L-TypeAdrenergic beta-AgonistsRats, Sprague-DawleyExcitation Contraction CouplingCell SizeCardiotonic AgentsSarcomeresSarcoplasmic Reticulum Calcium-Transporting ATPasesSarcolemmaSodium-Calcium ExchangerSarcoplasmic ReticulumPatch-Clamp TechniquesCalcium SignalingPhenylephrineConnexin 43Signal TransductionHypertrophyRyanodine Receptor Calcium Release ChannelAction PotentialsTime FactorsAtrial Natriuretic FactorDose-Response Relationship, DrugHeart AtriaMitochondria, HeartRabbitsMicroscopy, ConfocalCaffeineEnzyme ActivationPropanolaminesApoptosisMice, TransgenicMice, Inbred C57BLRNA, MessengerProtein Kinase CStimulation, ChemicalCalcium-Binding ProteinsCalcium ChannelsDisease Models, AnimalPhosphorylationDogsPhenylalanineReceptors, Adrenergic, betaEnzyme InhibitorsHeart FailureMice, KnockoutArrhythmias, CardiacIon TransportKineticsPhosphodiesterase InhibitorsGene ExpressionGap JunctionsGuinea PigsCyclic AMPAngiotensin IIBlotting, WesternCyclic AMP-Dependent Protein KinasesPotassium ChannelsCytosolCalcium Channel BlockersImidazolesTransfectionMitogen-Activated Protein Kinase 1Membrane PotentialsSodium ChannelsCell SurvivalIon Channel GatingMolecular Sequence DataColforsinCell DifferentiationCell LineAdenosine TriphosphateAgingImmunohistochemistryCell CountElectric StimulationMyocardial Reperfusion InjuryEmbryonic Stem CellsGene Expression RegulationGATA4 Transcription FactorAmino Acid SequenceBase SequenceOxidative StressDrug StabilityReverse Transcriptase Polymerase Chain ReactionIn Situ Nick-End LabelingMutationFreeze Drying