Expression of Neuronal and Inducible Nitric Oxide Synthase Isoforms and Generation of Protein Nitrotyrosine in Rat Brain Following Hypobaric Hypoxia

The expression of neuronal and inducible nitric oxide synthase (nNOS and iNOS) and nitrotyrosine immunoreactivities in the cerebral cortex caudate putamen islands of Calleja hippocampus superior colliculus and cerebellum of rats submitted to hypobaric hypoxia equivalent to an altitude of 30,000 feet (9144 m barometric pressure 230.4 Torr) were analyzed and semiquantitatively assessed by means of light microscopic immunocytochemistryand Western blotting using specific polyclonal antibodies. Changes in the expression of these components were directly related to the reduction of barometric pressure time of exposure to hypobaric hypoxia and the post-hypoxic recovery period. After exposure to hypobaric hypoxia for 8 h and a recovery period of 24 h an intense vasodilatation was also demonstrated in blood vessels throughout the brain and especially in blood vessels of the hypothalamic magnocellular accessory group.