Hyperoxic gas mixture is widely used in the clinic for the treatment of diseases.

However, it is known that with increasing levels of partial pressure of oxygen and duration of its effects various pathological processes may develop. There are only few published works dedicated to the effect of hyperoxic gas mixture on the functional activity of the lungs, which proves the relevance of such kind of investigations. Our purpose is to examine the changes of morphofunctional indicators on the respiratory part of the lung of young and adult rats after exposure to normobaric hyperoxic gas mixture.

The investigation of normobaric hyperoxic gas mixture (40% and 90% oxygen) influence was performed within 1 hour during 14 days to 42 male Wistar rats age of 3 and 12 months. All the manipulations with the animals were in accordance with “The European Convention for the Protection of Vertebrate Animals Used for Experimental and other Scientific Purposes” (Strasbourg, 18 March 1986). Histological preparations from the lung tissue were made by the standard method. Tissue samples were fixed in the Buen’s liquid, dehydrated in alcohols of increased concentrations and dioxan, embedded in paraffin. Sliced 5–6 μm thick, prepared using sliding microtome, were stained using the conventional method – Bemer hematoxilin and eosin, Van-Gizone and put into Canadian balm. Tissue specimens were analyzed under 100x magnification using light microscope with the eyepiece micrometer MOB-1-15x and the computer software IMAGE J. On the histological preparations of the lungs mean diameter, depth, cross-sectional area, entrance size of alveolus and the total width of respiratory bronchioles, alveolar ducts and alveolar sacs were measured. Statistical processing of morphometric results was done with the aid of analysis of variance by means of PC software Statiatica 6.0. Certainty of deviation between the control and the experimental groups was estimated using Student t-criterion.

After 14 daily hyperoxic sessions (40% and 90% oxygen), 60 min each, on the respiratory part of the lung rats of different age-dependent groups reduction in mean diameter, cross-sectional area and depth of alveoli was found. Increasing of the entrance size of alveolus and the total width of respiratory bronchioles, alveolar ducts and alveolar sacs in rats of 12 month of age were detected. So there is increase of respiratory bronchioles airiness and alveolar ducts, but decrease of alveolar surface area and alveolus airiness, after the exposure to hyperoxic gas mixture. Increasing of the amount of collagen fibers and the alveolar wall thickness in a lung after breathing the hyperoxic gas mixture was detected. These findings could indicate the connecting tissue growth in the respiratory part of the lungs and worsening of oxygen diffusion through the blood-air barrier. The investigated morphometric indexes on the respiratory part of the lungs changed to a greater degree in rats of 3 month of age, while rats of 12 month of age appeared to be less sensible to toxic influence oxygen.

Therefore, breathing the hyperoxic gas mixture of 40% and 90% oxygen reduces the total alveolar surface area, increases the mass of connective tissue on the respiratory part of the lung, which leads to the reduce of gas exchange rate and ventilation in lungs.

Ключові слова: normobaric hyperoxic gas mixture, respiratory part of the lung, alveolus

Повний текст: PDF (Ukr)