EnkephalinsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, LeucineEnkephalin, MethionineAnalgesiaAnalgesia, EpiduralEnkephalin, D-Penicillamine (2,5)-Enkephalin, Leucine-2-AlaninePeptidesAnalgesia, ObstetricalEndorphinsReceptors, Opioid, muReceptors, OpioidAnalgesia, Patient-ControlledAnalgesics, OpioidMorphineReceptors, Opioid, deltaReceptors, Neurokinin-3NaloxoneNeurokinin BEthylketocyclazocinePain, PostoperativeTachykininsReceptors, TachykininPeptide FragmentsCyclazocinePain MeasurementNarcotic AntagonistsAnalgesicsReceptors, Opioid, kappaD-Ala(2),MePhe(4),Met(0)-ol-enkephalinSubstance PBupivacaineFentanylNeurokinin AAnesthetics, LocalOligopeptidesOpioid PeptidesReceptors, Neurokinin-2Acupuncture AnalgesiaPeptide LibraryDynorphinsAmino Acid SequencePeptides, CyclicInjections, SpinalPainAntimicrobial Cationic Peptidesbeta-EndorphinSufentanilAnesthesia, EpiduralNaltrexoneRNA, Transfer, GlyMeperidineMolecular Sequence DataLabor PainDose-Response Relationship, DrugCarboxypeptidase HBenzeneacetamidesNarcoticsBenzomorphansProtein PrecursorsDrug ToleranceNerve BlockGuinea PigsPeptide MappingAmidesKineticsLabor, ObstetricAnesthesia, ObstetricalPiperidinesModels, MolecularProtein ConformationStructure-Activity RelationshipNeurokinin-1 Receptor AntagonistsDiprenorphineGlycineBinding SitesEtorphineAnalgesics, Non-NarcoticProtein BindingMorphinansPain ThresholdAnesthesia, SpinalDouble-Blind MethodRats, Sprague-DawleyVasoactive Intestinal PeptideReceptors, Neurokinin-1TramadolNatriuretic Peptide, BrainChromatography, High Pressure LiquidBase SequenceMorphine DerivativesBinding, CompetitiveNeprilysinBrainProtein Structure, SecondaryThiorphanCesarean SectionCalcitonin Gene-Related PeptidePostoperative Nausea and Vomiting