Myocytes, CardiacCell DifferentiationMyocardiumHeartCells, CulturedPerceptual DefenseMyocardial ContractionCardiomegalyCalciumAnimals, NewbornMuscle CellsSignal TransductionRats, Sprague-DawleyCardiac OutputRNA, MessengerArrhythmias, CardiacCalcium Channels, L-TypeGene Expression RegulationTime FactorsIsoproterenolTranscription FactorsStem CellsSodium-Calcium ExchangerVentricular FunctionRats, WistarGene Expression Regulation, DevelopmentalMice, TransgenicSarcolemmaCalcium SignalingCell LinePatch-Clamp TechniquesMice, KnockoutMice, Inbred C57BLCardiac Surgical ProceduresGuinea PigsSarcomeresCell SizeDeath, Sudden, CardiacSarcoplasmic ReticulumGene ExpressionMolecular Sequence DataHeart AtriaMuscle ProteinsMembrane PotentialsAdrenergic beta-AgonistsAction PotentialsMitochondria, HeartCell DivisionCell LineageDNA-Binding ProteinsCardiomyopathiesReverse Transcriptase Polymerase Chain ReactionImmunohistochemistryPhosphorylationEmbryonic Stem CellsSex DifferentiationBlotting, WesternModels, CardiovascularTransfectionCell ProliferationApoptosisBase SequenceReceptors, Adrenergic, betaPotassium ChannelsHeart FailureGATA4 Transcription FactorHeart DiseasesSarcoplasmic Reticulum Calcium-Transporting ATPasesCardiac Pacing, ArtificialPhenotypeCardiotonic AgentsRabbitsTranscription, GeneticEnzyme InhibitorsRyanodine Receptor Calcium Release ChannelCell SeparationDogsAtrial Natriuretic FactorMyosin Heavy ChainsMicroscopy, ConfocalDose-Response Relationship, DrugModels, BiologicalCalcium ChannelsMyoblasts, CardiacPromoter Regions, GeneticElectrophysiologyTretinoinEnzyme ActivationKineticsHomeodomain ProteinsMyocardial IschemiaProtein Kinase CCaveolin 3Cell Culture TechniquesCell SurvivalTroponin IPhenylephrineReceptors, Adrenergic, beta-1Cardiac MyosinsUp-Regulation