Sinoatrial NodeSinoatrial BlockTachycardia, Sinoatrial Nodal ReentryLymph NodesAtrioventricular NodeBiological ClocksBradycardiaHeart AtriaHeart RateRabbitsAction PotentialsAtrial FunctionHeart Conduction SystemHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsArrhythmia, SinusModels, CardiovascularCyclic Nucleotide-Gated Cation ChannelsVagus NerveSick Sinus SyndromeAtrial Function, RightCalcium Channels, L-TypeHeart BlockElectrophysiologyMembrane PotentialsCalcium Channels, T-TypeConnexinsTachycardia, SinusPotassium ChannelsDogsHeartElectrocardiographyIsoproterenolIon ChannelsConnexin 43Cardiac Pacing, ArtificialLymph Node ExcisionPatch-Clamp TechniquesMyocytes, CardiacMyoblasts, CardiacMicroelectrodesAminophyllineDelayed Rectifier Potassium ChannelsAdrenergic beta-AgonistsElectrophysiological PhenomenaGuinea PigsBenzazepinesSentinel Lymph Node BiopsyCardiac MyosinsPacemaker, ArtificialRyanodineArrhythmias, CardiacSodium ChannelsCardiotonic AgentsAutonomic Nervous SystemAging, PrematureAnti-Arrhythmia AgentsComputer SimulationTachycardia, SupraventricularSarcoplasmic ReticulumAcetylcholineSodium-Calcium ExchangerNatriuretic Peptide, C-TypeParasympathetic Nervous SystemCalciumCalcium SignalingAtropineIon Channel GatingElectrophysiologic Techniques, CardiacRyanodine Receptor Calcium Release ChannelMyocardial ContractionLymphatic MetastasisPhosphodiesterase 3 Inhibitors