Influence of Rat Exploratory Activity on Brain Oxygen Uptakein Vitro

Brain O2 uptake of rats that performed 25 minutes of exploratory activity was compared to that of inactive controls. Cortical slices and homogenates from the experimental group had lower endogenous O2 uptake than slices or homogenates from controls. The addition of glucose to the incubation medium stimulated the O2 uptake by both slices and homogenate but nullify the difference between the active and inactive animals. With [U-14C] glucose as substrate the homogenate from either group of rats did not differ significantly in the amount of 14CO2 produced. Endogenous O2 uptake of homogenates from the control group was not affected by the Ca++ concentration in the incubation medium. On the contrary, endogenous O2 uptake of homogenates from the experimental group was higher in a Ca++ free medium.The possible meaning of these changes is discussed in relation to the regulation of energy-yielding metabolism by environmental manipulation.