PhenylisopropyladenosineRubidium RadioisotopesHeartMyocardiumVentricular FunctionHeart VentriclesMusclesGuinea PigsMuscle ProteinsHeart RateMuscle, SkeletalMuscle, SmoothPapillary MusclesMuscle Fibers, SkeletalMuscle, Smooth, VascularMuscle DevelopmentHeart Septal Defects, VentricularMuscle ContractionMyocardial ContractionHeart FailureHeart DiseasesMitochondria, MuscleMuscle FatigueMuscle Fibers, Fast-TwitchMuscle DenervationMyofibrilsMuscle Fibers, Slow-TwitchMyocytes, Smooth MuscleMyocytes, CardiacHeart TransplantationHeart Defects, CongenitalCardiomyopathiesNeck MusclesOculomotor MusclesCalciumCardiomyopathy, DilatedMuscle, StriatedRabbitsMuscle SpindlesHeart AtriaMuscle RelaxationTime FactorsRespiratory MusclesMuscle WeaknessMuscle CellsFetal HeartAbdominal MusclesQuadriceps MuscleCells, CulturedCreatine KinaseElectric StimulationMasseter MuscleRats, Sprague-DawleyHeart ValvesRats, WistarFacial MusclesMasticatory MusclesDogsSarcomeresRNA, MessengerIntercostal MusclesElectromyographyMuscular AtrophyIsometric ContractionAnuraAction PotentialsFMRFamideSarcolemmaMyocarditisMembrane PotentialsPerfusionCatsSarcoplasmic ReticulumKineticsSatellite Cells, Skeletal Muscle