Postnatal behavioral consequences of antenatal intermittent hypoxia experienced during early organogenesis in mature rats

This study analyses the spontaneous behavior and anxiety-phobic status of mature rats that were subjected to antenatal intermittent hypoxia during the early stages of organogenesis. Antenatal intermittent hypoxia caused a decrease of motor activity as well as an enhanced anxiety level in rats of both sexes, while males appeared to be more sensitive to hypoxic influence. The effects of single antenatal intermittent hypoxia were more expressed than those of double exposure.     

Individual characteristics of external respiration during intermittent normobaric hypoxia

Correlation and regression relationships between the indices of the body responsiveness to hypoxic impacts and initial individual values of indices of the respiratory system and heart activity were studied in a group of subjects during three repeated cycles of breathing alternately a hypoxic gas mixture (11 vol % O₂) for 5 min and normal air for 5 min. A steady negative correlation between the most important regulatory indicator, the increase in the CO₂ content of the lungs, and its initial level in individual subjects was found. This may determine the known “normalizing” curative and prophylactic effects of intermittent normobaric hypoxia on the gas transport system of the body. A correlation between the individual increase in the CO₂ content of the lungs in response to hypoxia and changes in the heart rate and initial inhalation rate and depth, rather than oxygen consumption by the body, was found.     

The adaptational intracellular mechanisms regulating energy homeostasis during intermittent normobaric hypoxia]

Rats trained to intermittent normobaric hypoxia (INH) developed an increase of the glycogen contents in the heart and liver parenchymatous cells. Fatty acids seem to be the main source for synthesis of the intracellular glycogen. The intracellular transformation of the lipid energy substrate into the carbohydrates maintains the energy homeostasis in hepatocytes and cardiomyocytes during hypoxic intervals of the INH thus creating the necessary conditions. This kind of regulating the substance supply of the cell energy supports the organism stability under various effects.     

External respiration response of trained skiers to intermittent normobaric hypoxia

As part of a study on the resistance of subjects adapted to aerobic physical activity to hypoxia, the ventilatory response of trained skiers whose regular physical training is associated with hyperventilation to intermittent normobaric hypoxia has been analyzed. A test session consisted of three cycles of breathing alternately a hypoxic gas mixture (10 vol % O₂) for 5 min and normal air for 5 min. The skiers have a lower oxygen consumption rate as compared with untrained subjects, i.e., a reduced resistance to hypoxia. Therefore, the efficiency of respiration during hypoxia is lower in atheltes, which is caused by a rapid decrease in blood oxygenation, whereas during breathing normal atmospheric air, the efficiency of respiration is lower in untrained subjects.     

The effects of nightly normobaric hypoxia and high intensity training under intermittent normobaric hypoxia on running economy and hemoglobin mass.

We investigated the effects of nightly intermittent exposure to hypoxia and of training during intermittent hypoxia on both erythropoiesis and running economy (RE), which is indicated by the oxygen cost during running at submaximal speeds. Twenty-five college long- and middle- distance runners [maximal oxygen uptake (Vo(2max)) 60.3 +/- 4.7 ml x kg(-1) x min(-1)] were randomly assigned to one of three groups: hypoxic residential group (HypR, 11 h/night at 3,000 m simulated altitude), hypoxic training group (HypT), or control group (Con), for an intervention of 29 nights. All subjects trained in Tokyo (altitude of 60 m) but HypT had additional high-intensity treadmill running for 30 min at 3,000 m simulated altitude on 12 days during the night intervention. Vo(2) was measured at standing rest during four submaximal speeds (12, 14, 16, and 18 km/h) and during a maximal stage to volitional exhaustion on a treadmill. Total hemoglobin mass (THb) was measured by carbon monoxide rebreathing. There were no significant changes in Vo(2max), THb, and the time to exhaustion in all three groups after the intervention. Nevertheless, HypR showed approximately 5% improvement of RE in normoxia (P < 0.01) after the intervention, reflected by reduced Vo(2) at 18 km/h and the decreased regression slope fitted to Vo(2) measured during rest position and the four submaximal speeds (P < 0.05), whereas no significant corresponding changes were found in HypT and Con. We concluded that our dose of intermittent hypoxia (3,000 m for approximately 11 h/night for 29 nights) was insufficient to enhance erythropoiesis or Vo(2max), but improved the RE at race speed of college runners.     

Effect of intermittent normobaric hypoxia on gastric and duodenal mucosa in man]

Clinical and laboratory examinations of 11 patients with peptic ulcer have shown that combined treatment using sessions of intermittent normobaric hypoxytherapy (10% of oxygen in 90% of nitrogen, length of respiration is 7 min., respiration of free air 3 min., such 6 cycles for 1 hour) promotes healing of ulcers, decreases dyspepsic and astheno-neurotic symptoms of disease. The method can be recommended for treating the patients with peptic ulcer and for preventing seasonal acute attacks in patients with relapses of this disease.     

NO-dependent effects during adaptation of rats to intermittent hypoxia

In experiments on Wistar rats processes nitric oxide production on concentration of anions (NO2-, NO3-), carbamide and polyamines contents were investigated in processes of rats adaptation to acute hypoxia (7% O2 in N2, 30 min) and intermittent hypoxia training (10% O2 in N2, 15 min, 5 cycles daily) during 14 days. NO production by oxygen-dependent and oxygen-independent metabolites paths has been investigated. It is concluded that the disturbances in nitric oxide system induced by acute hypoxia by L-arginine injections may result in acute hypoxia.     

Influence of doxycycline administration on rat embryonic development during organogenesis

This experiment was performed to evaluate the possible embryotoxic and teratogenic effects of doxycycline during rat development. Twenty‐one female rats were used and distributed into three groups equally (seven animals/group). The low dose group received doxycycline at a dose of 5 mg/kg bw/day orally from the 6th to 14th day of gestation. The high dose group received 10 mg/kg bw/day orally for the same period, the Control group received 1 mL distilled water orally for the same period. The dams were dissected on the 20th day of gestation and their fetuses were subjected to morphological, skeletal, and histological examination. Moreover, DNA damage analysis of liver cells of pregnant rats and their fetuses or fetal skull was assessed by Comet assay. The obtained results showed a significant decrease in fetal body weight, several morphological anomalies, and severe lack of ossification on the skull bones, phalanges, and sternum bone as well as shortness in the ulna and radius bones. Histological studies of pregnant rats revealed congestion and dilatation of the central vein of the liver lobules and fatty degeneration of the hepatocytes. In addition, 20 day‐fetuses showed a marked increase of necrotic hepatocytes associated with an increased average of megakaryocytes and periportal leukocytic infiltration. Moreover, doxycycline induced a significant increase in the percentage of DNA damage and tail length of examined samples. Conclusively, doxycycline caused certain fetal abnormalities, so it is advisable to avoid using this drug during pregnancy.     

Response of subjects trained to hold their breath to intermittent normobaric hypoxia

The change in the external respiration parameters was studied in individuals engaging in sports (swimming) combined with training in voluntary cyclic breath holding during a session of intermittent normobaric hypoxia (three cycles of 5 min breathing a gas mixture containing 10.7% O₂ alternating with 5 min breathing ordinary air). It was shown that they differed from the control group in sharp variations in the oxygen consumption rate, which were accompanied by equally marked changes in the effectiveness of oxygen binding in the lungs with a slightly increased stable level of pulmonary ventilation and a bradypneic type of breathing. An increase in the alveolar concentration of carbonic acid and a dramatic increase in the effectiveness of its elimination are significant features of the adaptive process in the mechanism of regulation of external respiration in this training.     

Effect of intermittent normobaric hypoxia on dynamics of disease state in patients with hypertension]

Curative effect of intermittent normobaric hypoxia created when breathing in gaseous hypoxic mixture containing 10% of oxygen and 90% of nitrogen has been examined in 41 patients with hypertonic disease. Adaptation to hypoxia has been studied for its effect on the central hemodynamics psychoemotional state and kinetics of oxygen supply of the skin. The pronounced positive effect of treatment was achieved in 70.7% of patients, the arterial pressure decreasing at the expense of different mechanisms depending on the type of blood circulation. Besides, a decrease in the emotional tension of patients and normalization of oxygen consumption and transport were observed.     

Effect of intermittent normobaric hypoxic activity on the development of acute radiation disease]

The experiments on 260 male mice of colony SHK, 352 mongrel rats and 20 Wistar rats were carried out to study the ability of using the normobaric hypoxic stimulation method for acute radiation sickness. Hypoxic stimulation using gas mixture with 10% of oxygen and 90% of nitrogen was conducted for two weeks after irradiation for 30 min. every day. It is shown that under influence of ionizing radiation (7 and 5.5 Gy) the postradiation hypoxic action increased the 30-day survival rate of mice, reduced disturbances of the qualitative composition of leukocytes in peripheric blood, promoted more rapid restoration of thromboelastography indices and caused no reliable changes in the postradial content of albumin and creatinine in blood.     

Effect of prenatal hypoxia during organogenesis on albino rat behavior during postnatal period

The survival rate, physical development, and spontaneous behavior has been evaluated in pups of albino rats exposed to acute hypobaric hypoxia on the 9–10th day of gestation corresponding to the onset of organogenesis. Prenatal hypoxia increased the mortality among the offspring, delayed their physical development, and affected their spontaneous behavior up to the age of 2 months. The females exposed to intrauterine hypoxia proved to be more sensitive to hypoxia than males.