Figure 7. Effect of subcutaneous (SC) naloxone on morphine-induced hypoalgesia. A, Reversal of hypoalgesia by SC morphine, given at first arrow, to punctate stimulation by naloxone, given at second arrow. B, Reversal of SC morphine-induced hypoalgesia to nonpunctate stimulation by naloxone. C and D, Reversal of intrathecal morphine-induced hypoalgesia to punctate and nonpunctate stimulation by naloxone.