[Preadaption to nitrogen anesthesia and impairment of brain cortex structure in rats during hypoxia].

The attenuating effect of various variants of hypoxia on hyperbaric anesthesia in rats was studied. The most efficient turned out to be the daily 8-fold one-hour interval 6% hypoxia that decreased manifestations of the anesthesia by 60-67%. The immunocytochemical light optical microscopy showed that in the brain cortex after the 8th séance of such hypoxia the number of neurons with the strong and moderate reaction to heat shock proteins (HSP-70) increased essentially, whereas the number of neurons with the weak reaction to these proteins decreased significantly. After the first hypoxia séances the number of cells with no reaction for the nuclear protein NeuN increased, while after its 8th séance the areas of the absence of neurons appeared. It is believed that one of the main causes of an increase of resistance of the rat organism to nitrogen anesthesia after séances of the many-day interval 6% hypoxia is accumulation of HSP-70 in brain motor cortex cells. At the same time, taking into account a possible cell death and areas of deletion of neurons in cortex at use of the hypoxic action, it is better to use as a preadaptogen the more moderate or not too frequent hypoxia.

[Role of heat-shock proteins of Hsp70 family in changes of narcotic activity of hyperbaric nitrogen during increasing hypoxic stimulus].

The spontaneous motor activity and pose reflexes of male adult rats (Wistar) were observed in the course of high pressure nitrogen compression up to 4,1 MPa. The experiments were carried out under normoxic and hypoxic conditions. Stabile rat motor cortex oxygen tension was recording during the nitrogen compression up to 7,1 MPa under normoxic condition. Sensitivity to nitrogen high pressure to be on the increase under hypoxic conditions. In its turn, resistibility to nitrogen high pressure to be on the decrease under hypoxic conditions (oxygen partial pressure from 0,012 to 0,004 MPa). Quantity of high dencity heat shock proteins (Hsp70) rats motor cortex neurons was 3,44 times higher after course of high pressure nitrogen compression up to 4,1 MPa. For hypoxic exposure (6% O2) the difference was less pronounced - 2,2 times. Data about rat motor cortex neurons Hsp70 concentration under high nitrogen pressure and low oxygen pressure may turn to be a clear base for explanation hypoxic influence on processes of nitrogen narcosis.

[Effect of increased pressure of nitrogen on thermoregulation of mammals]. / Termoreguliatsionnye reaktsii mlekopitaiushchikh v usloviiakh deistviia povyshennogo davleniia azota.

Consumption of oxygen in rats was studied under conditions of the gas different ambient temperatures and pressure. A dependence was revealed between the neutral temperature and the high gas pressure. Mathematical model revealed an increase oxygen consumption at an increase gas pressure. The data suggest that the animal body temperature may be kept unaltered through an increased pressure of oxygen-nitrogen as a compensation of the heat transmission increased in an increased oxygen consumption.

The effect of increased nitrogen pressure on motor activity and the intercentral relationships of the brain of monkeys.

The influence of increased nitrogen pressure up to 19 ata was investigated in chronic experiments on monkeys of a species of Javan macaques (Macaca irus) with electrodes implanted in cortical and subcortical regions of the brain. The phasic character of the changes of motor activity of the animals, an increase in the spectral density of the average power of the EEG in the range of frequencies from 4 to 20 Hz, and a disturbance in the connectedness of the electrogenesis of the reticular formation of the midbrain with the bioelectrical processes in the substantia nigra, the head of the caudate nucleus, and the frontal and motoric areas of the cortex were identified in the course of nitrogen compression at a rate of 1.0 ata per 1 min.