Sinoatrial NodeSinoatrial BlockTachycardia, Sinoatrial Nodal ReentryLymph NodesAtrioventricular NodeBiological ClocksBradycardiaHeart AtriaHeart RateRabbitsAction PotentialsAtrial FunctionHeart Conduction SystemHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsArrhythmia, SinusModels, CardiovascularVagus NerveCyclic Nucleotide-Gated Cation ChannelsSick Sinus SyndromeAtrial Function, RightElectrophysiologyCalcium Channels, L-TypeHeart BlockMembrane PotentialsDogsConnexinsCalcium Channels, T-TypePotassium ChannelsTachycardia, SinusHeartElectrocardiographyIsoproterenolIon ChannelsConnexin 43Cardiac Pacing, ArtificialPatch-Clamp TechniquesLymph Node ExcisionMyocytes, CardiacMyoblasts, CardiacMicroelectrodesAminophyllineDelayed Rectifier Potassium ChannelsGuinea PigsAdrenergic beta-AgonistsElectrophysiological PhenomenaBenzazepinesSentinel Lymph Node BiopsyCardiac MyosinsSodium ChannelsPacemaker, ArtificialRyanodineArrhythmias, CardiacCardiotonic AgentsComputer SimulationAutonomic Nervous SystemAging, PrematureAnti-Arrhythmia AgentsSarcoplasmic ReticulumAcetylcholineTachycardia, SupraventricularSodium-Calcium ExchangerCalciumNatriuretic Peptide, C-TypeParasympathetic Nervous SystemCalcium SignalingIon Channel GatingAtropineElectrophysiologic Techniques, CardiacRyanodine Receptor Calcium Release ChannelTime FactorsMyocardial ContractionMice, KnockoutLymphatic MetastasisCell SizePhosphodiesterase 3 Inhibitors