Effect of hypoxia on the cerebral energy state.

The effect of hypoxia on glycogen content, adenyl cyclase activity, cyclic 3',5'-AMP concentration, lactate: pyruvate ratio and the energy charge potential connected with the pool of adenylates was evaluated in the motor area of the cortex of beagle dogs. At first, controlled hypoxia induces activation of the adenyl cyclase system while subsequently, with PaO2 values lower than 20 mm Hg, a depression of the system is observed simultaneously with a drop of the energy charge potential. When normal oxygenation is resumed, the biochemical parameters examined tend to go back to normal even though it is still necessary to resort to anaerobic mechanisms. The intracarotid perfusion with nicergoline enhances the post-hypoxic recovery of adenyl cyclase activity, even though the ergoline derivative is inactive during the stages of hypoxic suffering of the brain studied in the present work.