Myocardial ContractionHeartMyocytes, CardiacMyocardiumMuscle ContractionExcitation Contraction CouplingHeart VentriclesCalciumSarcomeresIsometric ContractionVentricular PressureDogsVentricular FunctionModels, CardiovascularIsoproterenolHeart RateSarcoplasmic ReticulumCoronary CirculationCardiomyopathiesRabbitsHeart DiseasesGene Expression Regulation, DevelopmentalUterine ContractionHeart Defects, CongenitalChick EmbryoHeart TransplantationRats, Sprague-DawleyCardiac OutputXenopus ProteinsTime FactorsElectrocardiographyMyocardial InfarctionEchocardiographyMuscle, SmoothArrhythmias, CardiacMorphogenesisTranscription FactorsCardiac Surgical ProceduresCell DifferentiationHomeodomain ProteinsIn Situ HybridizationMesodermDeath, Sudden, CardiacElectric StimulationMuscle, SkeletalBiological MarkersGuinea PigsCardiac Pacing, ArtificialVasoconstrictionCardiomegalyIsotonic ContractionCardiac TamponadeCardiac CatheterizationMuscle, Smooth, VascularMuscle RelaxationDose-Response Relationship, DrugNorepinephrineHeart ArrestMuscle FatigueElectromyographyRats, WistarHeart FailureMusclesPotassium ChlorideCardiac MyosinsVasoconstrictor AgentsPhenylephrineBlood PressureHemodynamicsGastrointestinal MotilityMyoblasts, CardiacTracheaAtropineVentricular Function, LeftAcetylcholineTroponin ICardiac GlycosidesCardiac Imaging TechniquesPeristalsisUrinary BladderCells, CulturedCardiac Output, LowMyosinsAorta, ThoracicNifedipineCardiac VolumeVentricular RemodelingAction PotentialsOut-of-Hospital Cardiac ArrestMyosin Light ChainsCardiotonic AgentsCalcium Channel BlockersHeart AtriaMyofibrilsPotassiumCarbacholStroke VolumeVas DeferensPapillary MusclesMuscle Tonus