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the structural changes in the cellular elements of the vessel wall remain unknown. Because of the simultaneous influences of cold and hypoxia at high altitude, people develop chronic obstructive pulmonary diseases (chronic obstructive bronchitis, chronic emphysema). It is therefore of interest to study the characteristics of vascular remodelling of the pulmonary circulation in these conditions.

The aim of study was to investigate the adaptive and non-adaptive structural changes of the pulmonary vessels during the development of HAPH and their characteristics in patients with COPD at high altitude. Tasks:

1. To reveal the characteristics of the morphology of the pulmonary vessels in native highlanders of Tien-Shan and Pamir.

2. To reveal the characteristics of structural changes in vessels of the pulmonary circulation in patients with some nosologic forms of COPD.

3. To determine the structural mechanisms of development of high altitude pulmonary edema as disadaptive state at high altitude.

Materials and methods. The lungs and hearts of 16 accidentally killed highlanders without pulmonary-related pathology were investigated. As a control the lungs and hearts of 5 health lowlander aboriginals were used. To study the structural changes of the pulmonary vessels the lungs and hearts of 10 deceased highlanders with COPD were investigated. As a control the lungs and hearts of 10 deceased lowlanders with COPD were used. Also, in 3 cases, the lungs and hearts of patients who died from high altitude pulmonary edema and in 2 cases - from high altitude pulmonary edema with COPD were investigated.

Volume of the right lung. For this, into the main bronchial tube was injected about 100 ml of 10% formalin solution. Then the lungs were submerged in formalin and after 2-3 days sections were cut from 3 zones of the right lung 2,5 x 3 x 1 cm in size. The lung sections were stained by hematoxylin-eosin and picrofuchsin-fuchselin.

For transmission electron microscopy, the sections were fixed in a 2.5% solution of glutaraldehyde in 0.1 M phosphate buffer. After additional fixing by 1% solution of four oxides of osmium, the sections were put into epoxy embedding medium. Ultra thin sections were examined by electron microscope PEM-100 after staining with citrate lead.

For scanning electronic microscopy, the pulmonary vessels were longitudinally dissected, dehydrated in ethanol of increasing concentration, dried up to transition of critical point and, after processing by palladium, examined on a scanning electron microscope "Philips-500".

Morphological methods: the method of separate weighing of heart by Muller, as updated by Kruchkova, was used. Thirty arteries and 30 arterioles from each zone of the lung were measured. For morphometry of the air haematic barrier, the negative components were used for electronogram by magnification x 20,000 on the basis of 25 measurements from each block.

Morphometrical ultrastructures were conducted according to the principles of stereologic analysis (Veibell, 1970; G.G.Avtandilov, 1981).

Statistical analysis. All quantity data were processed by methods of variational statistics.

Results and discussion. Characteristics of structural adaptive changes in the lungs of native highlanders, as result of the influence of chronic high altitude hypoxia, have been revealed. The expressiveness of adaptive morphological changes of the pulmonary vessels and right ventricular hypertrophy amplifies with increasing altitude. The weight of the right ventricle in native highlanders living over 3000 m above sea level was 10.1 ± 1.4 g (control - 6.8 ± 0.3 g, P < 0.002). Ventricle index reached 0.70 ± 0.03 (control- 0.42 ± 0.02, P < 0.002). This rate of right ventricular hypertrophy was close to the level of right ventricular hypertrophy in patients in the initial stages of COPD.

The morphometry of vessels in three zones of the right lung of native highlanders has detected redistribution of the bloodstream due to an increase in the upper and medial lobes. Though the morphometry of intral-obular and terminal pulmonary arteries in the upper and medial lobes has shown an increase in the volumetric speed of the bloodstream, there was an increase pulmonary-vascular resistance, due to an increase of pulmonary arterioles tone in all zones of the lungs. The functional parameter of vessels tone - the percentage of media to lumen (%) decreases in the central intral-obular and terminal arteries, especially in the upper and medial zones of the lungs, except for arterioles where the visible increase of this parameter in all zones of the lungs is noted.

Development of a longitudinal muscular layer is marked in the walls of the intralobular and terminal arteries of the upper and medial lung lobes in highlanders group living over 3000 m above sea level. These changes of the vessels level of resistance', in the form of lumen expansion and development of a longitudinal muscular layer, also have some similarity to changes in the pulmonary vessels in COPD.

In mechanisms of human adaptation to high altitude, the estimation of the phenomenon of the increase in capacity of the capillary bed of the alveolus has great value. The average diameter of the alveolar capillaries reached 13.0 ± 0.8 microns (control - 8.1 ± 0.4, P < 0.002). The increase in capacity of the capillary bed follows the primary expansion of their lumen and frequent occurrence of capillaries bulging adjoining to lumen with two alveoli.

Studying the endothelium ultrastructure of the alveolar capillaries has shown a twofold increase in the volumetric density of mitochondria, granules, granular endoplasmatic reticulum, microtubules and ribosomes. The hypertrophy of the pulmonary endothelium can be considered as a compensative adaptive reaction, which is a new qualitative level of functioning (figure 1).

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