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.     

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.     

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.     

Influence of intermittent normobaric hypoxia during early organogenesis on the development of white rats

The influence of antenatal intermittent normobaric hypoxia during early organogenesis (days 9–10 of intrauterine development) on the physical development, vegetative balance, and antioxidant defense system of 60-day-old rats was studied. Antenatal exposure to intermittent hypoxia resulted in the impaired physical development of all offspring during the early 15-day postnatal period and caused changes in the vegetative balance of heart regulation, which were differently directed in males and females. Moreover, females that survived antenatal hypoxia had a decreased superoxide dismutase activity in the brain, compared to that in the control rats.     

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.     

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.     

Brain circuits regulating energy homeostasis

Recent years have seen an impetus in the study for central mechanisms regulating energy balance, and caloric intake possibly as a response to the obesity pandemic. This renewed interest as well as drastic improvements in the tools that are now currently available to neuroscientists, has yielded a great deal of insight into the mechanisms by which the brain regulates metabolic function, and volitional aspects of feeding in response to metabolic signals like leptin, insulin and ghrelin. Among these mechanisms are the complex intracellular signals elicited by these hormones in neurons. Moreover, these signals produce and modulate the metabolism of the cell at the level of the mitochondria. Finally, these signals promote plastic changes that alter the synaptic circuitry in a number of circuits and ultimately affect cellular, physiological and behavioral responses in defense of energy homeostasis. These mechanisms are surveyed in this review.     

Physiological premises and mechanisms of normalizing effect of normobaric hypoxia and inhalation therapy]

Pathogenetic and physiological aspects of hypoxia problems have been considered. An opinion is stated that normalizing effect of intermittent normobaric hypoxia (INH) with short-term respiration of gaseous mixture containing at least 10% of oxygen in nitrogen is based on biorhythm inherent in all the living organisms with replacement of the high functional activity periods by the periods of rest and restoration with temporary physiological hypoxia as their typical companion. It is shown that for numerous diseases the course of INH or sessions of staying in the chamber of artificial mountain climate normalize the state of central nervous system, blood circulation, respiration, hemopoiesis and immunological reactivity, activate natural protective mechanisms and increase functional reserves of the organism. Allowing for anthropogenic pollution of the environment and its consequences for the health, it is advisable to widely adopt hypoxytherapy and orrhotherapy.     

Results of utilization of intermittent normobaric hypoxia in patients with bronchial asthma and chronic obstructive bronchitis]

The results of intermittent normobaric hypoxytherapy in 42 patients with bronchial asthma (BA) and 14 patients with chronic obstructive bronchitis (COB) are analyzed. The positive effect is obtained in 76% of patients with BA and 92.8% of patients with COB. In the group of patients with BA the best effect was achieved for atopic form of BA--in 90% of patients, the effect was less pronounced for infection-allergic form--in 73.9% and for mixed form of BA--in 66.7%. In the process of treatment the attacks of asphyxia disappeared or became more occasional in 60.7% of patients; in 32.1% the attacks were more easily arrested or stopped independently; 33.8% of patients decreased doses of constantly taken drugs; in 33% cough ceased or decreased, sputum became to expectorate better; in 41% of patients dyspnea disappeared and considerably decreased. Improvement of the state in 54% of patients was retained for one year and more, in 29%--for 6 months, in 16.6%--for 3-4 months. The course of treatment consisted of 20-25 sessions. The patients breathed in hypoxic gas mixture containing 10% of oxygen (HGM-10) under intermittent conditions alternating with respiration of free air.     

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.     

Physiologic bases of the method to increase nonspecific resistance of the organism by adaptation to intermittent normobaric hypoxia]

Impulse biorhythm of cyclic pO2 change in the uterus tissues and intrauterine fetus of rats, guinea pigs and dogs is regarded as evolution-fixed, physiological mechanism aimed at increasing nonspecific resistance of the fetus. Modeling of this mechanism by adaptation to intermittent normobaric hypoxia under impulse conditions permits more significantly increasing nonspecific resistance of the organism than application of hypoxic effect under constant conditions.     

State of the free-radical oxidation system in normobaric hypoxia]

The experiments on the rats have revealed that 7-hour action of 10% hypoxic gas mixture (HGM-10) exerts no effect on the parameters of Fe(2+)-induced chemiluminescence and rate of accumulation of TBA-active products in the heart, liver, kidney, brain tissues and blood plasma. Two-week adaptation to intermittent effect of HGM-10 causes some activation of free-radical oxidation recorded in blood plasma and the more pronounced increase in power of the endogenic antioxidant system. It is assumed that the revealed changes in the state of the homeostatic system of free-radical oxidation and antiradical protection of the organism are of importance in the mechanism of the known preventive and curative action of intermittent normobaric hypoxia.