to evaluate the effects of dynorphin a ( 1-13 ) pretreatment on the bradycardic response to iv morphine , rats were pretreated with 10 micrograms dynorphin a ( 1-13 ) icv four , six or eight hours prior to challenge with morphine sulfate ( 0.1 mg/kg iv ) .
C0026549
morphine
C0066814
morphine sulfate