Brain enzyme adaptation to mild normobaric intermittent hypoxia

Publisher Website
Google Scholar
Abstract
The adaptation of repeated periods of intermittent normobaric hypoxia (oxygen:nitrogen = 10:90, 12 hr daily for 5 days) of some specific enzymatic activities related to energy metabolism has been observed in different rat brain areas (cerebral cortex, hippocampus, corpus striatum, hypothalamus, cerebellum, and medulla oblongata). The evaluation of the maximum rate (Vmax) of the enzymes was carried out on: (1) the homogenate “in toto,” (2) the nonsynaptic mitochondrial fraction, and (3) the crude synaptosomal fraction. The adaptation to inermittent normobaric hypoxic exposure was characterized by significant modifications of some enzyme activities in the homogenate “in toto” (decrease of hexokinase activity in cerebellum), in the nonsynaptic mitochondrial fraction (increase of succinate dehydrogenase activity in corpus striatum and decrease of cytochrome oxidase activity in cererbral cortex), and, particularly, in the synaptosomal fraction (decrease of cytochrome oxidase activity in cerebral cortex, hippocampus, corpus striatum, and cerebellum, and decrease of malate dehydrogenase and lactate dehydrogenase activity in cererbellum). The adaptation to normobaric intermittent hypoxia differs according to the brain area, subcellular fraction, and enzyme activity tested.