THE INFLUENCE OF HYPOXIA ON THE FORMATION OF AMINO-ACIDS FROM OXIDIZED SUBSTRATES IN THE RAT-BRAIN INVIVO

Hypoxia can influence the development of pathological processes in the brain not only through the decrease of oxidative phosphorylation but also by synthesis and release of excitatory amino acids and GABA. We studied the influence of hypobaric (pO2 8.6 kPa) and normobaric hypoxia (pO2 5.27 kPa) on the transformation of U-C-14 glucose and 2-C-14 acetate into some amino acids connected with the tricarboxylic cycle. Hypobaric hypoxia and normobaric hypoxia have different effects on metabolic processes in neuronal and glial cells. The formation of the studied amino acids from U-C-14 glucose (neuronal compartment) was more decreased than the formation of amino acids from 2-C-14 acetate (glial compartment). This could be a consequence of higher sensitivity of neuronal than glial mitochondria to oxygen deficit or a result of uncoupling of amino acid formation in neurones. An unchanged synthesis of glutamine from acetate in glial cells during hypoxia may result in a protective metabolic effect.