Receptors, Opioid, kappa3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-IsomerReceptors, Opioid, deltaIsomerismRuthenium CompoundsStereoisomerismPyrrolidinesBenzeneacetamidesDiprenorphineRutheniumEnkephalin, D-Penicillamine (2,5)-Narcotic AntagonistsDiterpenes, ClerodaneNaltrexoneReceptors, OpioidAnalgesics, Non-NarcoticReceptors, Opioid, muOrganoplatinum Compoundsalpha-Linolenic AcidAnalgesics, OpioidBenzomorphansReceptors, PhencyclidineChromatography, GasOrganometallic CompoundsMagnetic Resonance SpectroscopyEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Fatty Acids, UnsaturatedChromatography, High Pressure Liquid