[Changes in the blood vessels of the lungs under physical loads at high altitude]. / Izmeneniia krovenosnykh sosudov legkikh pri fizicheskikh nagruzkakh v usloviiakh vysokogor'ia.

Changes of the pulmonary artery branches in rats at the state of relative physiological rest undergo two stages during the process of individual adaptation for 60 days. The first is characterized with generalized decrease of the lumen and with thickening of the vascular wall as a result of reflectory spasm and edematous swelling of the arteries, the second--with a relative dilatation of the lumen and with decreasing thickness of the vascular wall, as a result of decreasing reflectory spasm and edematous phenomena. The physical load increases the organism's elevated oxygen consumption under conditions of high-altitude, which is increased by itself; this intensifies the function of the pulmonary blood bed. In combination with the edematous phenomena, the wall of the pulmonary artery becomes sharply thickened in the first stage. In the second stage the tissue mechanisms are switched on for satisfaction of oxygen consumption. Therefore, the load on the right part of the heart and on the pulmonary vessels decreases edematous phenomena, the thickness of the wall in the pulmonary artery branches decline, in comparison with the data of the first stage. The thickness of the wall in the first stage is combined with a manifested constriction of the lumen, and the relative thinning of the vascular wall--with dilatation.

[Plasticity of blood vessels of the heart and lungs in collateral circulation under conditions of high altitude]. / Plastichnost' krovenosnykh sosudov serdtsa i legkikh pri okol'nom krovotoke v usloviiakh vysokogor'ia

The combination of the collateral blood flow in the heart and lungs with effects of Alpine hypoxia and pronounced additional loads was found to allow the detecting of plastical capacities of these organs in a sufficiently full volume. The experiments were performed in 273 dogs by microscopic, macro-microscopic, macroscopic and partly functional methods. The collateral coronary blood flow (after ligation of the anterior interventricular artery) under Alpine conditions (3200 m over the sea level) combined with compensatory hyperfunction of the heart (due to stenosing of the aorta arc), gets worse as compared with the conditions of the valley. In these experiments in mountains the extra- and intraorganic anastomoses are more pronounced, the capacity of the coronary artery branches being less pronounced than in the valley. The muscle fibres grow thicker, the heart weight enlarges, the diffusion distances of capillaries increase and the ratio of the arterial bed capacity and the heart weight decreases. Under Alphine conditions (as compared with the valley) the collateral blood flow of lungs deteriorates (after ligation of two lobar branches of the pulmonary artery or of the lobar vein) against the background of additional loads (stenosing of the aorta arc or pulmonectomy). Deterioration of the collateral bloodflow is related with the combination of conditions of the alphine hypoxia with additional loads resulting in a weakening or even block of compensatory reactions of pulmonary or bronchial arteries and veins.