TetrodotoxinSodium Channel BlockersSodium ChannelsRats, Sprague-DawleyAction PotentialsNeuronsCalcium Channel BlockersSaxitoxinPotassium Channel BlockersMembrane PotentialsVeratridineAngiotensin II Type 1 Receptor BlockersSodiumElectric StimulationAtropineCalciumGuinea PigsMuscle ContractionPotassiumElectrophysiologyMuscle, SmoothTetraodontiformesPatch-Clamp TechniquesIon ChannelsNifedipineTetraethylammonium CompoundsVeratrineFishes, PoisonousProtoveratrinesSynaptic TransmissionDose-Response Relationship, DrugVerapamilHexamethoniumGuanethidineElectric ConductivityTetraethylammoniumAcetylcholineAnesthetics, LocalPotassium ChannelsHexamethonium CompoundsRats, WistarLidocaine4-Aminopyridine