Metabolic changes during and after transient clamping of carotid arteries in normotensive rats

In the present experiments changes of local metabolism in the striatum, hippocampus, and frontal cortex during and after transient clamping of carotid arteries in normotensive rats (BCCA) were studied by continuous measurement of local cerebral temperature, partial oxygen tension (PO2), and extracellular levels of lactate. Local temperature in the striatum, hippocampus, and frontal cortex fell between 1.7 and 2.3 degrees C upon occlusion and quickly returned to preocclusion values after free flow had been established. Local PO2 was reduced in the striatum, hippocampus, and frontal cortex to values between 70 and 30% during BCCA. Immediately after termination of BCCA the PO2 showed a tendency to recover in the striatum and frontal cortex, whereas in the hippocampus, this process started later. Extracellular levels of lactate within these three structures increased during BCCA and went down to preocclusion values within the observed period of reperfusion. The results suggest that BCCA induces a transient anaerobic metabolism that seems to be sufficient to evoke functional changes without neuronal damage.