PentobarbitalAdjuvants, AnesthesiaRats, WistarSodiumInjectionsGABA ModulatorsHypnotics and SedativesBarbituratesSodium ChannelsAnestheticsChloraloseInjections, IntravenousEuthanasia, AnimalReceptors, GABA-AAnesthesiaXylazineDiazepamDose-Response Relationship, DrugInjections, IntramuscularSodium, Dietary