tolerance develops to morphine bradycardia after s.c. infusions of morphine sulfate ( e.g. , 74 nmol/hr/rat s.c. for 2 days elevated the morphine ed50 by 22 times ) , but not after central infusions of morphine at doses which are sufficient to produce physical dependence and tolerance to morphine analgesia .
C0066814
morphine
C0026549
morphine