Figure 1.

(A–D) The change in body temperature produced by an acute challenge with morphine (10 mg/kg) in guinea pigs implanted with either placebo- or morphine-containing pellets at various time periods. Morphine produced a modest hypothermia that was not apparently altered by chronic treatment with morphine. (E) The calculated AUC values for the hypothermic effect of morphine in guinea pigs implanted with morphine pellets. The values were used to evaluate the total magnitude of the response to morphine (10 mg/kg). Ratios of AUC values were determined and are presented in Table 1. Statistically significantly different values are indicated by (*).