Comparative effects of dextroamphetamine and reserpine on halothane and cyclopropane anesthetic requirements

Cyclopropane minimum alveolar concentration (MAC) values in dogs following intravenous administration of 0.5, 1 or 2 mg/kg of dextroamphetamine were 27.8, 28.4, and 28.4 volumes percent, respectively. Those values did not differ significantly from each other but were 44 percent greater than average control (no dextroamphetamine(MAC values. Halothane MAC values following the same dextroamphetamine doses were 1.51, 1.71, and 1.64 volumes percent. These values were 75 percent greater than average controls, and this increase was significantly more than the 44 percent noted with cyclopropane. In contrast, 2 mg/kg of reserpine decreased halothane MAC 20 percent vut decreased cyclopropane MAC 40 percent- the difference between the two anesthetics again being statistically significant. These results suggest that alteration of anesthetic potency by centrally active adrenergic drugs depends on the sympathetic activity induced by the anesthetic. Conversely, this suggests that anesthetics may influence their own potency by altering central nervous system adrenergic activity.