Oxygen regime in rat brain tissues under conditions of acute nitrite methemoglobinemia

Oxygen regime in rat brain tissues was studied under conditions of nitrite hypoxia. The local brain circulation (LCC) and pO₂ were recorded by polargraphic method in microareas of the brain cortex one hour after a subcutaneous injection of NaNO₂ (3 mg/100 g body mass). A LCC decrease by 55% was shown by the 30th min of the nitrite intoxication, with its restoration to 85% of the initial blood-flow by the 60th min. In some brain microareas, a pO₂ increase by 40.7% was observed by the 45th min of the action and its decrease by 32.2% by the 60th min, whereas in other microareas, a pO₂ decrease by 24.5% with its subsequent increase to 78.7% of the initial level, respectively. A statistically significant correlation is revealed between changes of the oxygen pressure in the process of development of nitrite hypoxia and the LCC dynamics. It is concluded that the circulatory disturbances developing at the first moments of the nitrite action lead to an increase of the degree of the pO₂ differentiated distribution in the brain: to hyperoxygenation in some microareas and to severe hypoxia in others, what can be the cause of functional brain disturbances under the effect of nitrogen oxides.