ClonidineInjectionsAdrenergic alpha-AgonistsAdrenergic alpha-2 Receptor AgonistsYohimbineInjections, IntravenousInjections, SpinalPreanesthetic MedicationSympatholyticsReceptors, Adrenergic, alpha-2Injections, IntramuscularAdrenergic alpha-AntagonistsImidazoline ReceptorsReceptors, Adrenergic, alphaAnalgesicsGuanfacineInjections, EpiduralInjections, SubcutaneousInjections, Intra-ArticularInjections, IntraventricularInjections, IntralesionalInjections, IntraperitonealIdazoxanAdrenergic alpha-2 Receptor AntagonistsAdjuvants, AnesthesiaDose-Response Relationship, DrugNorepinephrineBlood PressureOxymetazolineAnesthetics, LocalPrazosinHeart RateRats, Sprague-DawleyPhentolamineInjections, Intra-ArterialMorphineAnalgesia, EpiduralPremedicationDouble-Blind MethodReceptors, AdrenergicInjections, IntradermalDioxanesTime FactorsNaloxoneHemodynamicsIntravitreal InjectionsBupivacaineEpinephrinePain MeasurementDrug InteractionsHypnotics and SedativesNeostigmineGuanabenzLidocaineInjections, JetPain, PostoperativeRats, Inbred StrainsSympathetic Nervous SystemInjections, IntraocularPainMedetomidineMicroinjectionsAnalgesics, OpioidDexmedetomidineMethoxamineMethyldopaDesipramineRats, WistarImidazolesLocus CoeruleusShiveringDisease Models, AnimalAlfentanilAdrenergic AgonistsAnesthesia, Spinal