This work demonstrates that there is a biphasic effect on brain tissue respiration with respect to time interval after chlorpromazine administration to an intact animal. The first phase, lasting about 16 hours in the rat, reflects an inhibition of respiratory activity while the second, persisting about 4 days, reflects an enhancement of respiration. It is not clear at this point whether this biphasic effect is due to a peculiarity of metabolic activity or simply represents a different rate of penetration into cortical and subcortical structures.We have demonstrated that chlorpromazine can induce opposite effects on brain tissue respiration in different parts of the brain. The hemispheres including the cerebellum show an increased respiration while the midbrain and stem show a depression of respiration following chlorpromazine administration.Abstract Teaser