Membrane PotentialsMyocardiumCell MembraneMusclesHeartMuscle ProteinsMembranesMyocytes, CardiacIntracellular MembranesMembrane LipidsCells, CulturedCalciumMuscle, SkeletalMuscle, SmoothMembranes, ArtificialMyofibrilsMuscle Fibers, SkeletalCell Membrane PermeabilityMyocardial ContractionMembrane Potential, MitochondrialHeart VentriclesMicroscopy, ElectronErythrocyte MembraneCardiomegalyTime FactorsMyocytes, Smooth MuscleMembrane FluidityMuscle ContractionSarcomeresPotassiumRats, Sprague-DawleyGuinea PigsSarcolemmaMuscle, Smooth, VascularMuscle CellsMolecular Sequence DataSignal TransductionRabbitsMuscle DevelopmentBasement MembranePapillary MusclesActinsSarcoplasmic ReticulumCell LineAnimals, NewbornElectrophysiologyModels, BiologicalSodiumMitochondriaAction PotentialsKineticsBase SequenceFluorescent Antibody TechniqueAtrial Natriuretic FactorGene Expression RegulationElectric ConductivityGATA4 Transcription FactorMyosinsHydrogen-Ion ConcentrationTransfectionIon ChannelsMitochondria, HeartAdenosine TriphosphateMembrane Transport ProteinsCatsMembrane GlycoproteinsCell DifferentiationMitochondrial MembranesLipid BilayersPatch-Clamp TechniquesRNA, MessengerProtein BindingGene ExpressionHeart AtriaChick EmbryoProtein TransportCarrier ProteinsAmino Acid SequenceRats, WistarDose-Response Relationship, DrugDogsPotassium ChannelsCardiac OutputMicroscopy, FluorescenceMutationElectric StimulationFluorescent DyesBlotting, WesternAortaCattleMicroscopy, ConfocalBiological Transport, ActiveMuscle Fibers, Fast-TwitchElectrophoresis, Polyacrylamide GelMitochondria, MuscleChloridesLiposomesTranscription, GeneticCalcium ChannelsSynaptic Membranes