Резюме

Залюбовська О.І., Березнякова М.Є., Литвинова О.М., Зленко В.В., Фоміна Г.П., Карабут Л.В., Березняков А.В. Динаміка структурно-метаболічних змін в легенях інтактних щурів в умовах гіпербаричної оксигенації.

Досліджено динаміку структурно-метаболічних змін в легенях інтактних щурів в умовах гіпербаричної оксигенації. Встановлено, що в умовах гіпербаричної оксигенації стимулюються процеси біохімічного метаболізму в тканинах легені, підвищується рівень антиоксидантного захисту, сурфактант-продукуючої функції, що створює умови для стабілізації легеневого обміну.

Ключові слова: гіпербарична оксигенація , метаболізм тканин легені , газообмін.

Резюме

Залюбовская О.И., Березнякова М.Е., Литвинова О.Н., Зленко В.В., Фомина Г.П., Карабут Л.В., Березняков А.В. Динамика структурно-метаболических изменений в легких интактных крыс в условиях гипербарической оксигенации.

Исследована динамика структурно-метаболических изменений в легких интактных крыс в условиях гипербарической оксигенации. Установлено, что в условиях гипербарической оксигенации стимулируются процессы биохимического метаболизма в тканях легкого, повышается уровень антиоксидантной защиты, сурфактант-продуцирующей функции, что создает условия для стабилизации легочного обмена.

Ключевые слова: гипербарическая оксигенация, метаболизм тканей легкого, газообмен.

Summary

Zalubkivska O.I., Bereznyakova M.Y., Lytvynova O.M., Zlenko V.V., Fomina H.P., Karabut L.V., Bereznyakov A.V. Dynamics of anatomic-metabolic changes in lungs of intact rats under conditions of hyperbaric oxygen treatment.

The dynamics of anatomic-metabolic changes in lungs of intact rats under conditions of hyperbaric oxygen treatment was researched. It was found that under conditions of hyperbaric oxygenation treatment the processes of biochemical metabolism in the lung tissues are stimulated, the level of the antioxidative protection increases the same as the surfactant-producing function that creates the conditions for pulmonary gas exchange stabilization.

Key words: hyperbaric oxygenation, lungs tissues metabolism, gas exchange.

UDC 616.12-008.318-06:612.013.7

DYNAMICS OF ANATOMIC-METABOLIC CHANGES IN LUNGS OF INTACT RATS UNDER CONDITIONS OF HYPERBARIC OXYGEN TREATMENT

O.I. Zalubovskaya, M.E Bereznykova, O.N. Litvinova, V.V. Zlenko,

G.P. Fomina, L.V. Karabut, A.V. Bereznyakov

National University of Pharmacy, Kharkov

postavnaya@list.ru

Introduction

The research of the lung tissues anatomic substrate under conditions of hypoxia continues to draw attention because the character and intensity of such damages is the reason of the lung inability to response on the overload during the period of adaptation under conditions of hyperbaric oxygenation treatment (HOT).

Thus, until nowadays the question of HOT treatment whiles the pneumonia and acute respiratory failure wasn’t clarified [5.7]. Contraindications for HOT treatment in such cases are mostly based on the results of histological researches that indicate about the possibility of toxic effect of high-flow oxygen on the lung tissue anatomic structure [2.11]. And also there are not a lot of information in the literature about the       pulmonary gas exchange condition and metabolism while HOT treatment.

Goal: research of dynamics of anatomic-metabolic changes in lungs of intact rats under conditions of hyperbaric oxygen treatment.

Connection of the research with the science programs, plans, projects. These researches were conducted in accordance with the research plan of National University of Pharmacy under the title “Finding of general laws of pathological processes and development of its correction”.

Materials and research methods

The experiments were conducted on 95 rats – males with the weight of 200-250 gr. Animals were put into the hyperbaric chamber and were treated once with HOT. The continuance of treatment for the first group (25 rats) was two hours, for the second group (25 rats) – four hours, for the third group (24 rats) – seven hours. The control group had 21 rats. In the main groups gas exchange function, surfactant activity and pulmonary metabolism were researched. The evaluation of the pulmonary gas exchange was conducted on the basis of oxygen partial pressure in arterial blood probe (РаО₂), which was received by the puncture needle from the left ventricle and was tested by the microaerotonometer  «Corning М - 165» (England). The evaluation of the system surfactant activity was conducted in accordance with stability index of the foam bubble, squeezed from different parts of the lung [6.10]. The evaluation of the pulmonary metabolism was conducted on the basis of       glucocorticoid receptors level detection (of II type) in the pulmonary cytosol with the help of labeled acetonide triamcinolone (22 Ki/ mmol) and by the analogical hormone, which concentration was 200 times higher than the same of the labeled acetonide triamcinolone [3]. Corticosterone level in the blood plasma was detected with the help of the standard sets of «Sorin». While the anatomic research optical and electronic microscopy were used. The evaluation of the mentioned parameters and anatomic research of the lungs were conducted in two stages: part of animals had it in 20 minutes; another part of animals had it in 24 hours after the HOT treatment.

Results received and its discussion. While the 2-hours influence of HOT there were no significant changes of PaО₂ corticosterone level in the blood and surfactant activity in lung tissues of rats in comparison with control group. The level of cytosol in lungs increased accurately (see Table). With the help of the electronic microscopy the alveolar septum edema was discovered. In 24 hours after two-houred influence of HOT there were no changes of the lung tissues. After the 5-houred HOT influence РаО₂ decreased, surfactant activity and glucocorticoid receptors level (of II type) in lungs, the corticosterone concentration in blood (see Table). With the help of the microscope the places with      interstitial edema, mitochondria swelling in alveolocytes of II type with the damage of organelles in it.  In 24 hours after 5-houred HOT influence РаО₂ wasn’t significantly different from the same index in the control group, but surfactant activity increased. The consistence of corticosterone in the blood of animals in this group decreased almost in two times, and the consistence of pulmonary glucocorticoid receptors increased, while it still was lower than the control group. The anatomical changes of the lungs were saved completely. After the 8-houred HOT influence the РаО₂ index dropped significantly, surfactant activity and glucocorticoid receptors level (of II type) in lungs also dropped, which were accompanied by the corticosterone concentration increase in blood plasma of this group animals. Anatomic changes of lungs right after the HOT treatment of animals in this group were maximally expressed.

Gas exchange indexes, surfactant activity and metabolism in the lung after the HOT treatment (М±m)

Note. Probability of indexes difference in comparison with the control is р <0,05.

Macroscopically there were found atelectasis parts, hemorrhages, in some cases even pulmonary edema signs, which were confirmed by the data of world and electronic microscopy. In 24 hours after 7-houred HOT treatment the РаО₂ level was still low; it was caused by the formation of stabile arterial hypoxemia, which is the same while, the acute respiratory failure. However, surfactant consistence and glucocorticoid receptors in the rats’ lungs increased dramatically and reached the level shown by the control group. Corticosterone concentration in the blood until this time decreased more than 7 times and wasn’t dramatically different from the indexes of the control group. Anatomic changes of lungs in 24 hours after the HOT treatment were saved completely [9].

In such a way, received data showed probable toxic influence of HOT on physiological and anatomic-metabolic indexes that reflect the lungs condition. As the given data showed, the state of exposed anatomic-functional changes was characterized by the significant duration of the HOT treatment. The mechanisms of HOT toxic influence was conditioned first of all by the  free radical formation  of superoxide anion  type (О₂), its protonated form (НО₂),         hydrogen dioxide (Н₂О₂), hydroxyl radical (PO). They are created through the     catecholamines self-oxidation, thiols, hemoglobin tetrahydroptheryne and also with the enzyme help, that catalyze the univalent oxygen recovering [4.9]. Newly formed free radicals “attack” not only important lipid substrates of the intermediate metabolism, but also cell structures that have SH – groups and nucleic acids [9]. The surfactant system, which is directly connected with the oxygen transportation lungs function, has the most sensitivity for the    peroxidation products [2.9]. It may be considered that while the 2-houred HOT treatment the system of endogenic antioxidative protection (α-tocopherol, superoxide dismutase, glutathione peroxidase, catalases) ensures the inactivation of       superoxide radicals and hydroperoxides not only in lungs, but in the whole body. Otherwise, the body responds with the stress-reaction with the increase of the corticosterone level [1.4]. While the 2-houred HOT treatment the level of corticosterone in blood changed significantly, and the content of glucocorticoid receptors in lungs even increased. Accordingly to the literature data [9], the increase of tissue receptors content is possible only in the conditions of macro ergs, such as adenosine triphosphate. Maybe under the influence of 2-houred HOT treatment the nucleotide biosynthesis happened. The ability of adenosine triphosphate to activate the glucocorticoid receptors is described by the list of authors [4.6]. Therefore, there is a positive influence of HOT in these conditions on macro ergs, which ensures higher energetic potential of the organism. In the case of continuous HOT treatment (4 hours) the endogenic antioxidative system doesn’t ensure inactivation of superoxidative radicals and hydroperoxides, the result is the stress-reaction, which demonstrates itself with the high level corticosterone in the blood. High level of glucocorticoids in the blood during this period should be considered as the adaptive process, as the glucocorticoids, on one hand, increase the metabolism in the lungs through the receptor mechanism, and on the other hand, they give the membrane stabilizing effect, which prevents     hydrolyzing enzyme lysosomes mobilization [4.8] .

In 24 hours after 4-houred presence in the hyperbaric chamber the rats showed the significant rehabilitation of pulmonary gas exchange function and the relevant РаО₂ increase. Despite the structural damages the surfactant restores completely – alveolocytes’ producing function of II type. As the analysis of the received data showed, the stress-reaction also ensures the restoring of metabolic indexes in the lung tissue and in the blood of animals after the 7-houred HOT treatment.

Conclusion

In the result of the research it was found that in the case of the significant anatomic-functional disorders of the lung tissue under conditions of hyperbaric oxygenation treatment the biochemical processes are stimulated the same as the antioxidative protection, surfactant-producing action, which creates the precondition of the pulmonary gas exchange stabilization.