[Mechanisms of changes of microcirculation in rats under acute methemoglobinemia].

It was investigated the features of microcirculation and mechanisms it's conditioned, under acute administration of sodium nitrite in 5 mg of dry substance per 100 g of body weight. It was shown that acute administration of sodium nitrite leads to the development of methemoglobinemia, arterial and venous hypoxemia, and severe tissue hypoxia. Increase in the diffusion path O2 at methemoglobinemia is caused due to significant hyperhydratation of lung air-blood barrier and its individual layers, and is accompanied by a decrease in both components of the diffusion capacity of the lungs for oxygen: its membrane and blood components. It was revealed that the administration of sodium nitrite has a double effect, leading to inactivation of hemoglobin, as well as to microcirculatory disturbances associated primarily with changes in the regulation of vascular tone. In this initial perfusion per unit volume of tissue per time unit intrinsic for the organism defines a set of mechanisms which are responsible for changes in tissue blood flow under methemoglobinemia.