[Effect of calcium channel blockers on developing nervous syndrome of high pressure and nitrogen narcosis in mice].

In the experiments conducted on mice which prior to compression in a heliox environment have been injected the blockers of various types of calcium channels (flunarezine, verapramil and nifedipine) as well as bemethyl (actoprotector) and oxymethacye (antioxidant) there escaped detection of noticeable effect of these drugs on developing the high pressure nervous syndrome (HPNS). On exposure to the hyperbaric nitrogen-oxygen environment verapromil (phenylalkulamine blocker of L-type calcium channels) had a protection effect with respect to a convulsive component of the nitrogen narcosis.

[Prediction of the central effect of pharmacological preparations in a hyperbaric environment].

A new method for predicting the central effects of pharmacological preparations in hyperbaric helio- and nitrogen-oxygen environments takes into consideration the dynamics of changes in excitability of different structures of the brain in animals compared with EEG and behavioural symptoms of the high pressure nervous syndrome (HPNS), and levels of the barometric pressure. The concept of the central effect of preparations under hyperbaric conditions should be taken into account while rendering the medicamentous assistance to aquanauts directly exposed to elevated pressure. Besides, it was shown that the strategy of searching protectors against NSHP and nitrogen narcosis may consist of selecting substances which will adequately recuperate shifts in the brain excitability due to these hyperbaric pathologies.

[Involvement of adrenergic mechanisms in developing the nervous syndrome of high pressure and nitrogen narcosis].

Involvement of the adrenergic mediator system in central mechanisms of hyperbaric nitrogen narcosis or the high pressure nervous syndrome (NSHP) produced by nitrogen or heliox gas mixtures under increased pressure was studied in mice and rabbit experiments with the use of pharmacological substances-analyzers. Accumulated data are indicative of lack of a significant role of the adrenergic system in the NSHP genesis and a protective effect of activation of the central but not peripheric adrenergic mediation in development of the behavioural and electrophysiological symptomatics of nitrogen narcosis. Mechanisms of NSHP and nitrogen narcosis and possible principles of pharmacological correction are under discussion.

[The function of the brain structures in rabbits under the action of hyperbaric helium and nitrogen-oxygen mixtures].

Behaviour of rabbits as well as excitability thresholds of certain brain areas were determined by intracranial electrostimulation under high pressure in the heliox and nitrox media. Excitability of the mesencephalic reticular formation and of the frontal cortex in particular, decreased under 11 ata in the nitrox medium. On the contrary, measurements of the thresholds and EEG data have shown an increase in excitability in all brain regions under 41 ata of the heliox medium.

[The effect of adren-, cholin- and dopaminergic preparations on the formation of the high-pressure nervous syndrome in rabbits].

Behaviour and the EEG responses to electric intracranial stimulation of the frontal cortex, mesencephalic RF, dorsal hippocampus and caudate nucleus were studied in hyperbaric experiments in rabbits. Thresholds of the stimulation for all the areas were decreased at 41 ATA, the thresholds progressively decreasing at 71 and 101 ATA. Preliminary administration of various pharmacological agents activating and inhibiting different neurotransmitter systems, altered the regularity of the EEG changes and behaviour.