Study of changes in the parameters of peripheral blood vessels of the arterial bed during an orthostatic test in hypoxic hypoxia

There were performed studies of reovasography of the lower leg and foot pools to identify possible mechanisms of various reactions from the heart and Central hemodynamics in hypoxia to orthostatic load. The dependence of changes in the parameters of Central hemodynamics in response to various environmental factors on the properties of resistive vessels is shown. Key words: The orthostasis, hypoxic exposure, rheovasography, rheographic index, vascular tone.

EFFECTS OF PHYSICAL STRESS ON VISUAL ACUITY IN THE PLAIN AND MOUNTAIN CONDITIONS

Научная статья посвящена установлению изменений со стороны зрительных функций у студенток старших курсов очно-заочной формы обучения в условиях гипоксической и динамической гипоксии. В период акклиматизации к гипоксической гипоксии в течение пятнадцати дней наблюдалась волнообразность или двухфазность изменения остроты зрения. Повышение с первого по пятый день и постепенное снижение с десятого по пятнадцатый день. Scientific article is devoted to establishing changes on the part of visual functions in students of senior courses of full-time education in conditions of hypoxic and dynamic hypoxia. During the period of acclimatization to hypoxic hypoxia, waviness or two-phase change in visual acuity was observed for fifteen days. Increase from day one to day five and gradual decrease from day ten to day fifteen.

Study of renal function indices to determine hypoxic hypoxia resistance in divers

Aim: using oral stress kidney tests to reveal changes in renal function and water-electrolyte metabolism in divers with different initial resistance to hypoxic hypoxia.Materials and methods. 44 men were studied. All subjects were evaluated for their initial resistance to hypoxic hypoxia. Oral renal stress tests were performed to determine the status of kidney function.Results and their discussion. For the selection of divers, it is necessary to carry out oral stress tests with water, 10% potassium chloride solution and 7.5% calcium lactate solution. In divers with low and medium resistance to hypoxic hypoxia, there is a deterioration in the calcium and potassium uretic function of the kidneys after oral stress renal tests. The method for determining the resistance of divers to hypoxic hypoxia should be supplemented by the regularity developed by us.

The Protective Effect of Para-Aminobenzoic Acid in HypoxiaInduced Apoptosis of Conjunctiva and Cornea Cells in vivo

Purpose: to evaluate the effects of acute hypoxic hypoxia on eye tissue cells in adult rats and determining the effectiveness of 0.007 % solution of para-aminobenzoic acid (PABA) for apoptotic damage to the tissues of the ocular surface in rats.Materials and methods. In the experiment, 27 male Wistar rats (54 eyes) were used, divided into 5 groups. Group I — intact control, Group II — hypoxic control after 1 hour, Group III — hypoxic control after 3 hours, Group IV — with the injection of the drug 1 hour after hypoxia, Group V — injection of the drug 24 hours before hypoxia. The identification of apoptotic cells in the tissues of the eye was performed by the TUNEL method on frozen sections of the eye stained with Hoechst 33342 nuclear fluorescent dye. The localization and fluorescence intensity of the damaged cells was analyzed under a fluorescence microscope using the Image J. computer program.Results. Under the conditions of simulated acute hypoxic hypoxia, apoptotic lesions of the conjunctiva, corneal epithelium, choroid, and photoreceptor layer of the retina were observed. In group II, the number of damaged cells in the conjunctiva was 67 %, and in group III it was 120 % more compared to group I — the norm (p < 0.05). With the injection of PABA before hypoxia, there were no significant differences compared with the norm (group I) in the state of the affected cells in the conjunctiva. In the group of animals (group III) with the injection of PABA after hypoxia after 1 h, the number of damaged cells does not statistically differ from group II (hypoxic control after 1 h), but significantly lower than in group III (hypoxic control after 3 hours). The same pattern is observed in the corneal epithelium.Conclusion. Para-aminobenzoic acid (0.007 %) has a prophylactic and therapeutic effect, preventing and stabilizing the development of apoptosis of conjunctival cells and anterior corneal epithelium induced in experimental acute hypoxic hypoxia.

Ratio of venous-to-arterial PCO2 to arteriovenous oxygen content difference during regional ischemic or hypoxic hypoxia

The purpose of the study was to evaluate the behavior of the venous-to-arterial CO2 tension difference (ΔPCO2) over the arterial-to-venous oxygen content difference (ΔO2) ratio (ΔPCO2/ΔO2) and the difference between venous-to-arterial CO2 content calculated with the Douglas’ equation (ΔCCO2D) over ΔO2 ratio (ΔCCO2D/ΔO2) and their abilities to reflect the occurrence of anaerobic metabolism in two experimental models of tissue hypoxia: ischemic hypoxia (IH) and hypoxic hypoxia (HH). We also aimed to assess the influence of metabolic acidosis and Haldane effects on the PCO2/CO2 content relationship. In a vascularly isolated, innervated dog hindlimb perfused with a pump-membrane oxygenator system, the oxygen delivery (DO2) was lowered in a stepwise manner to decrease it beyond critical DO2 (DO2crit) by lowering either arterial PO2 (HH-model) or flow (IH-model). Twelve anesthetized and mechanically ventilated dogs were studied, 6 in each model. Limb DO2, oxygen consumption ($${\dot{\text{V}}\text{O}}_{2}$$ V ˙ O 2 ), ΔPCO2/ΔO2, and ΔCCO2D/ΔO2 were obtained every 15 min. Beyond DO2crit, $${\dot{\text{V}}\text{O}}_{2}$$ V ˙ O 2 decreased, indicating dysoxia. ΔPCO2/ΔO2, and ΔCCO2D/ΔO2 increased significantly only after reaching DO2crit in both models. At DO2crit, ΔPCO2/ΔO2 was significantly higher in the HH-model than in the IH-model (1.82 ± 0.09 vs. 1.39 ± 0.06, p = 0.002). At DO2crit, ΔCCO2D/ΔO2 was not significantly different between the two groups (0.87 ± 0.05 for IH vs. 1.01 ± 0.06 for HH, p = 0.09). Below DO2crit, we observed a discrepancy between the behavior of the two indices. In both models, ΔPCO2/ΔO2 continued to increase significantly (higher in the HH-model), whereas ΔCCO2D/ΔO2 tended to decrease to become not significantly different from its baseline in the IH-model. Metabolic acidosis significantly influenced the PCO2/CO2 content relationship, but not the Haldane effect. ΔPCO2/ΔO2 was able to depict the occurrence of anaerobic metabolism in both tissue hypoxia models. However, at very low DO2 values, ΔPCO2/ΔO2 did not only reflect the ongoing anaerobic metabolism; it was confounded by the effects of metabolic acidosis on the CO2–hemoglobin dissociation curve, and then it should be interpreted with caution.

ENDURANCE OF HYPOXIC HYPOXIA AFTER PRELIMINARY BREATHING OF NORMOXIC MIXTURES CONTAINING ARGON OR KRYPTON

The purpose was assessment of the possibility to increase mammal's endurance of hypoxic hypoxia by preconditioning through breathing normoxic gas mixtures (BGM) containing argon or krypton. Preconditioning by krypton-containing BGM one or two hours prior to hypoxia (initial О2 concentration of 20.8 %) increased endurance of oxygen starvation. Preconditioning by argon-containing BGM did not bring this effect. Immediately after hypoxia several animals in both the test and control groups displayed a short-time generalized tremor that grew in the nitrogen – argon – krypton (N2 – Ar – Kr) succession consistently with their narcotic activities. This effect can be ascribed to modification by Ar and Kr of the humoral and neuronal tremor reactions to the hypoxic stress. Testing the preconditioning effect of Kr-containing BGM prior to hypoxia with the initial О2 concentration of 14.6 ± 0.40 % also demonstrated a decrease of minimal endurable О2 concentration although less evident. Effects from normoxic Kr-containing BGM correlates with the time space between preconditioning and hypoxia.

TECHNOLOGIES OF AUTOMATED NOTIFICATION OF HUMAN HEALTH AND PERFORMANCE RISKS UNDER HYPOXIC HYPOXIA

The technologies of automated notification of health risks and human performance under hypoxic hypoxia are described, which provide the calculation and presentation in real time of visual and acoustic information about the value of the assessment of the reserve time for maintaining human health and performance under hypoxic hypoxia