Delayed recovery of CO2 reactivity after one hour's complete ischaemia of cat brain.

The cerebrovascular CO2 reactivity was examined after 6 h, 1, 2, and 3 days and 1 year following 1 h complete brain ischaemia in the cat. After 6 h recirculation, the CO2 reactivity was completely suppressed although major EEG activity had recovered. After 2 days, CO2 reactivity began to reappear, but even after 1 year restitution was not complete. The prolonged (though partly reversible) attenuation of CO2 responsiveness suggests that ischaemia is followed by a long-lasting state of haemodynamic imbalance, which may be responsible for the slow progress of post-ischaemic recovery processes.