SystoleHeartMusclesMyocardiumHeart RateMuscle ProteinsMuscle, SkeletalMuscle, SmoothMyocardial ContractionPapillary MusclesMuscle Fibers, SkeletalMuscle, Smooth, VascularMuscle DevelopmentMuscle ContractionHeart FailureHeart DiseasesDiastoleMitochondria, MuscleHeart VentriclesMuscle FatigueMuscle Fibers, Fast-TwitchMuscle DenervationMyofibrilsVentricular FunctionHeart AtriaMuscle Fibers, Slow-TwitchMyocytes, CardiacTime FactorsDogsCardiomyopathiesEchocardiographyCardiomyopathy, DilatedMyocytes, Smooth MuscleFetal HeartCalciumHeart TransplantationModels, CardiovascularHeart Defects, CongenitalRabbitsVentricular Function, LeftNeck MusclesOculomotor MusclesMuscle, StriatedMuscle SpindlesMuscle RelaxationRespiratory MusclesMuscle WeaknessAtrial FunctionMuscle CellsBlood Flow VelocityHemodynamicsElectric StimulationAbdominal MusclesHeart BlockMitral ValvePerfusionQuadriceps MuscleEndocardiumCells, CulturedCreatine KinaseMasseter MuscleCardiomegalyRats, Sprague-DawleyStroke VolumeHeart Function TestsHeart ValvesKinetocardiographyRats, WistarEchocardiography, DopplerFacial MusclesMasticatory MusclesCardiac VolumeSarcomeresMyocardial IschemiaRNA, MessengerCardiomyopathy, HypertrophicGuinea PigsIntercostal MusclesElectromyographyMuscular AtrophyIsometric ContractionAnuraAction PotentialsOxygen ConsumptionFMRFamideSarcolemmaMyocarditisMembrane PotentialsCatsIsoproterenolSarcoplasmic ReticulumKineticsSatellite Cells, Skeletal MuscleHeart InjuriesHeart SeptumRegenerationCardiotonic AgentsPectoralis MusclesAtrial Function, LeftCoronary Disease