[Properties of NAD-dependent brain enzymes under the conditions of hypoxia and ischemia].

The catalytic properties of mitochondrial and cytoplasmic isoenzymes of NAD-dependent brain malate dehydrogenase (MDH) were studied under hypoxic or ischemic conditions. Hypoxia was modeled in animals in pressure chamber, while ischemia was achieved via bilateral ligation of common carotic arteries. The properties of MDH in mitochondria of rat brain were studied; they were significantly different from those of MDH purified from bovine brain. The study revealed the importance of mitochondrial membranes for the regulation of malate dehydrogenase catalytic properties in brain mitochondria. Cerebral ischemia changes mitochondrial malate dehydrogenase significantly, which demonstrates disorder in MDH-membrane interaction. Cytoplasmic enzyme displays high activity and stability of its catalytic properties. Under cerebral hypoxia or ischemia catalytic properties of cytoplasmic malate dehydrogenase change only slightly, maintaining enzyme activity at a constantly high level.