Muscle ContractionMuscle, SmoothIsometric ContractionGuinea PigsUterine ContractionNifedipineCalciumMuscle TonusElectric StimulationVas DeferensCalcium Channel BlockersH-ReflexMuscle RelaxationVasoconstrictionCaffeineMuscle, Smooth, VascularAdrenergic alpha-Agonists15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidMyocardial ContractionIleumPotassium ChloridePhenylephrineCarbacholPotassiumUrinary BladderNorepinephrineAtropineElectromyographyHexamethonium CompoundsRyanodineAcetylcholineTracheaGallbladderRabbitsStomachDose-Response Relationship, DrugIndolesAorta, ThoracicMembrane PotentialsTetrodotoxinProstaglandinsDogsEnzyme InhibitorsMuscle, SkeletalIsotonic ContractionMuscle FatigueTonic PupilMusclesTime FactorsGastrointestinal MotilityAction PotentialsRats, Sprague-DawleyMotor NeuronsVasoconstrictor AgentsRats, WistarPeristalsisCatsTorqueSerotoninMyosin Light Chainsrho-Associated KinasesBiomechanical PhenomenaElectrophysiologyReflexMesenteric ArteriesNeural InhibitionMuscle Fibers, SkeletalPressureMyosinsVerapamilReceptors, GABA-AHistamineMyometriumHeartRecruitment, NeurophysiologicalAdenosine TriphosphateMyographyVolitionArteriesIndomethacinKineticsManometryMyocardiumPrazosinParasympatholyticsEsophagusReflex, StretchDecerebrate StateNeurokinin ACells, CulturedMuscarinic AntagonistsEndothelinsModels, BiologicalEndothelin-1Papillary MusclesElbowAdrenergic alpha-AntagonistsPeriodicityPatch-Clamp TechniquesMyofibrils