ARTIFICIAL HYPOBIOSIS AS A METHOD OF G-FORCE NEGATIVE IMPACT REDUCTION
Authors:   FSBSI «Izmerov Research Institute of Occupational Health», Makarov A.F. , Tkachuk Y.V. , Shishkov A.Yu. 
Published: September 2023

Dynamic gravitational acceleration, known as a G-force, is an extreme factor for some professions. G-force negative impact realizes in central nervous system adequate functioning disturbance, resulting from oxygen starvation of tissues due to hemodynamic disorders. Known methods of G-force protection are aimed at increasing the maximum short-term G-force value, but not its total safe duration. In a number of studies, in order to increase the maximum value of the tolerated G-force, laboratory animals were lead in to a state of artificial hypobiosis. Mortality decrease was noted with an increase the maximum G-force value. Data about the manifestations of disorders of the central nervous system and the recovery time, as well as changes in the safe G-force duration has not been detected. The study purpose to assess the change in the safe G-force duration while artificial hypobiosis. Materials and methods. Syrian male hamsters weighing 95.5±0.5 g (M±m) were used. The animals were divided into groups — experimental and control. Intramuscular injections of a suspension of α-methyldopa were performed to induce artificial hypobiosis in animals of the experimental group. The control group received of 0.9% NaCl. Dynamic gravitational acceleration modeling was carried out using a centrifuge (r=0.62 m). The animals of both groups were conscious, with positive G-forces pointing downward (head-pelvis). Within 10 seconds (s), the centrifuge rotation speed was increased till the chosen G-force value, G: 30 (angular velocity (ω)=21.79 rad/s), 40 (ω=25.16 rad/s) or 70 (ω=33.28 rad/s). G-force exposure set time, s: 20, 50, 80, 110 or 140. After a complete stop for 10 seconds, the general condition of the animals, injuries, hemorrhages, breathing, heart contractions were assessed. The surviving animals were monitored, consciousness was assessed, coordination disorders were determined according to the following criteria: animal’s pose, productive movement, unsteady gait, circle movement, tilting; Also, the time of restoration of coordination was determined. The animals were observed during the following days to assess the daily survival rate. Necropsy was performed on all non-surviving animals. Results. Survival in the control group: 30 G: 80 s — 5/6, 40 G: 20 s — 6/6, 50 s — 6/6, 80 s — 3/6, 70 G: 20 s — 6/6, 50 s — 4/6, 80 s — 0/10. Survival in the experimental group: 70 G: 50 s — 6/6, 80 s — 10/10, 110 s — 10/10, 140 s — 2/6. After acceleration of 70 G 50 s in animals of the experimental group, coordination disorders were weakly expressed, the coordination recovery time was 1.8±0.3 s, in animals of the control group, violations were assessed as significant, the recovery time was 4.5±0.3 s, which is 2.5 times (p<0.01) more. Next day: tremor persisted in 3 animals of the control group 40 G 80 c. In the remaining animals of all groups, no coordination disorders were found. No external injuries were observed in any animal. No organ or skeletal damage was found during necropsy. Conclusions. An increase of 5.5 times in the time of safe stay of animals in a state of artificial hypobiosis under dynamic overloads has been proven. There was a 2.5‑fold decrease in the coordination recovery time in animals in a state of artificial hypobiosis.