Muscle ContractionMusclesMuscle, SkeletalPhosphocreatineElectromyographyElectric StimulationAdenosine TriphosphateModels, BiologicalIsometric ContractionUterine ContractionMyocardial ContractionMuscle, SmoothIsotonic ContractionVasoconstrictionCalciumGuinea PigsMuscle, Smooth, VascularMuscle RelaxationMuscle FatiguePotassium ChlorideGastrointestinal MotilityTracheaVasoconstrictor AgentsPeristalsisUrinary BladderNorepinephrineDose-Response Relationship, DrugAcetylcholineRabbitsAtropinePhenylephrineVas DeferensIleumNifedipineAorta, ThoracicMuscle TonusCarbacholTorqueRats, WistarDogs15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic AcidMyosin Light Chainsrho-Associated KinasesTime FactorsRats, Sprague-DawleyMotor NeuronsSerotoninCaffeineMyometriumCalcium Channel BlockersMesenteric ArteriesMuscle Fibers, SkeletalMyosinsPotassiumVerapamilHistamineAdrenergic alpha-AgonistsMyographyManometryIndomethacinEnzyme InhibitorsBiomechanical PhenomenaArteriesCatsVolitionEsophagusPrazosin