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FIG. 3. Effects of multiple doses of either l-ephedrine or d-amphetamine on core body temperature. (Top) Core body temperature after 3 doses, given at 3-h intervals, of either 1 ml/kg ip saline or 40 mg/kg l-ephedrine at an environmental temperature of 22–23°C. The increased variability in the 3 x 40 mg/kg l-ephedrine group 2 h after the initial dose are due to the intervention of cooling the rats on crushed ice when body temperatures rose to 41.5°C or above after the first or second dose. There was a significant interaction of drug and time (the F test yielded a value of F9, 80 = 4.288 p < 0.001), and post hoc analysis indicated that, at all time points after the initial dosing, temperatures of the l-ephedrine group were significantly higher than saline-treated controls (p < 0. 01, Tukey's test). (Bottom) Temperature changes after 4 consecutive doses, given at 2-h intervals, of 1 ml/kg ip saline, 25 mg/kg l-ephedrine, or 5 mg/kg d-amphetamine at an environmental temperature of 22–23°C. Variations in core body temperature were not as great in the 4 x 25 mg/kg l-ephedrine and 4 x 5 mg/kg d-amphetamine groups as the 3 x 40 mg/kg l-ephedrine group (shown in top graph). This was because most rats given either 4 x 25 mg/kg l-ephedrine or 4 x 5 mg/kg d-amphetamine did not need to be cooled with ice (body temperatures remained lower than 41.5°C) until after the third or fourth dose. A 2-way ANOVA showed that both the drug treatment and time-after-initial-dose factors affected body temperatures (F2,70 = 15.56, p < 0.001). Both drug-treated groups (amphetamine and l-ephedrine) had body temperatures that were significantly greater than the saline group at all time points after dosing (p < 0.001, Tukey's test). However, body temperatures of the ephedrine and amphetamine groups did not differ from one another at any time point (F1, 70 = 2.768, p < 0.101).
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