[The tissue oxygen partial pressure in organs of hens in the second half of embryogenesis and in the first days after hatching].

The aim of the study was measure the development chick tissue partial pressure of oxygen (pO2) in the brain cerebral hemispheres, liver, M. pectoralis, M. gastrocnemius, and to estimate the correlation of this index with our previously measured values (laser-Doppler flowmetry) volume blood flow (BF) in these organs. We studied 10-, 15-, and 19-day embryos and 4-day chickens thatwere anesthetized with urethane. pO2 measurements were made in thesurface layers of organs by the membrane amperometric Clark-type O2-electrode with a diameter of about 50 microm of the cathode placed in the center of the sensor with an outer diameter of 3.4 mm. Disclosed noticeable distinction of both the organ tissue pO2 values, and the dynamics of their changes duringthe study period. The most important of them: (1) the lowest pO2 (and BF) is observed in the brain and particularly in the liver of 10-day embryos; (2) in the subsequent period of embryogenesis pO2 in the brain increases 1.9 times (rising and BF) in M. pectoralis it falls by 1.7 times and in the liver.and in M. gastrocnemius changes little wherein the BF in both liver and muscles is not changed, (3) after hatching pO2 in the liver and M. petoralis fold increased (also increasing and BF), and in the brain and M. gastrocnemius, despite the increase BF (greater in the niuscle) did not significant change. In the analysis ofthedata are considered two possible mechanisms of change of tissue pO2 in the developing organs of chickens, one is due to the peculiarities of intracardiac blood flows; and the other is related to thesingularity of the oxyhemoglobin dissociation in the blood capillary bed of organ, determined by the specifics of its oxidative metabolism.

[Rat heat structural and functional characteristics and gas exchange parameters after experimental myocardial infarction].

Rat heart structural and functional changes and gas exchange parameters were investigated in six months after experimental myocardial infarction. Left ventricular end-systolic and end-diastolic dimensions in rats with chronic heart failure were 78 and 30% higher than in control respectively. Left ventricle cavity volume in systole and diastole were 5 and 2 times increased respectively. Left ventricular cavity stretching was accompanied by thinning of the interventricular septum. Left ventricular structural changes leads to its functional deterioration. Left ventricular contraction fraction was reduced by 60%, and the ejection fraction--by 52% in comparison with control. Gas exchange investigation revealed that in six month after myocardial infarction oxygen consumption of operated rats was increased by 30% and production of carbon dioxide by more than 40%. Respiratory quotient, which reflects the nature of oxidized substrates, in rats with myocardial infarction was amounted to 0.85, indicating significant increase in the contribution of carbohydrates as an energy substrate for myocardial metabolism.

[Changes of gas exchange parameters and of functional-biochemical properties of erythrocytes in dynamics of experimental anemia in rats].

In experiments on Wistar male rats, on a specially constructed computer installation, O2 consumption by the animals in comparison with changes of hematological, biochemical, and rheological blood properties is studied after anemization--acute bloodletting (12-15% of the total blood mass). An increase of the O2 consumption by the organism and tissues by 18-28% has been revealed for the first 7 days after the bloodletting, in spite of a pronounced decrease of hematocrit, and of the amount of erythrocytes and hemoglobin in peripheral blood by 20-25% of the initial level. There was a 5-10-fold increase of the content of immature erythrocyte forms--reticulocytes and a progressive rise of cell acidic resistance, which is characteristic of young erythrocyte forms. An increase of O2 consumption at a decrease of the blood oxygen capacity (a low hemoglobin level) seems to be due to the more efficient transport and yield of O2 to tissues. At the 3rd 7th day after the bloodletting, activity of Na,K-ATPase has been shown to increase by 60% and 20%, respectively. Analysis of the erythrocyte rheological properties has shown that the maximal firmness of aggregates (Uq) and the aggregation rate (1/T) decrease progressively beginning from 3 days after the bloodletting; index of deformability (I(max)) turned out to be elevated by 7-11%, probably due to an increase of the cell membrane elasticity. The conclusion is made that changes of erythrocyte rheological properties are interconnected with changes of the Na,K-ATPase activity and are directed to optimization of blood circulation in large vessels and the capillary network.

[The dynamics of milk secretion in white mice and its consumption by progeny]. / Dinamika sekretsii moloka u belykh myshei i ego potreblenie potomstvom.

Only about 72 per cent of the litter manifested milk ingestion during every next nursing in white mice. The correlation between the dynamics of the milk ejection from the mammary gland and individual real milk intake by the litter, is discussed.

[Changes in the water-salt composition of alveolar and ductal milk in the white mouse when accumulated in the mammary gland]. / Izmenenie vodno-solevogo sostava al'veoliarnogo i protokovogo moloka beloi myshi pri ego nakoplenii v molochnoi zheleze.

The ion and water contents revealed a 25-41% lower Na level in the duct than in alveolar secret in lactating albino mice through 1 to 7 and 24th hour of suckling. The data obtained suggests dynamic properties of alveolar and duct epithelium in mice.

[The dynamics of the transepithelial transport of sodium, potassium and water in the mammary gland of the white mouse]. / Dinamika transépitelial'nogo perenosa natriia, kaliia i vody v molochnoi zheleze beloi myshi.

In lactating albino mice, the transepithelial mammary transport of Na+, K+ and water was studied during normal and changed intervals between suckles. The formation of ion and water contents of the mice milk usually occurs in 2 stages N first, all Na+, 1/4 K+ and 1/3 water contents in ready milk enter the secret of mammary gland; second, the Na+ in milk is stopped and net flow of K+ and water is 3- and 2-fold higher than during first stage.

[Fluctuations in local blood flow and oxygen tension in the alveolar complexes of the mammary gland in the course of the secretory cycle]. / Kolebaniia lokal'nogo krovotoka i napriazheniia kisloroda v al'veoliarnykh kompleksakh molochnoi zhelezy v khode sekretornogo tsikla.

In lactating albino mice, an interrelationship was found between rhythmic changes of the blood flow intensity and oxygen supply of secretory cells in all the alveoles during secretory cycle. The maximal value of the local blood flow (134 +/- 30 ml/100 g.min) and the minimal O2 tension level (27.5 +/- 2.8 mm Hg) were observed in the alveolar complexes at the initial stage of the secretory cycle when the oxygen consumption was the most intense in the alveolar cells. The minimal value of the local blood flow (44 +/- 2 ml/100 g.min), and the maximal O2 tension level (42.8 +/- 2.1 mm Hg) were recorded during the middle interval (30-35 min) of the secretory cycle with the lowest speed of O2 consumption in the alveolar cells. The data obtained suggest that asynchrony of function and blood supply of adjacent alveoles enables to provide secretory cells with O2 in an optimal way during different periods of their activity.

[Patterns of the redistribution of sodium, potassium and water in the tissues of lactating white mice]. / Zakonomernosti pereraspredeleniia natriia, kaliia i vody v tkaniakh laktiruiushchikh belykh krys.

The Na+ concentration on the blood plasma of lactating mice increased by 22%. The muscle ion and water contents were unchanged in lactation whereas K+ level was increased by 15% in the red cells, the Na+ concentration - by 23% in mammary alveolar tissue, K+ - 2.5 times and water - 1.5 times as high as non-lactating animals. The data obtained suggest that: 1) the mechanism maintaining the cell Na+ concentration is sufficiently effective in lactation, 2) there is an interrelationship between the cell ion-water content and the degree of the rise in specific activity of the tissue during lactation, 3) Na+ enters the milk by a paracellular way in the mouse mammary gland in vivo after suckling.

[Patterns of redistribution of calcium and magnesium in the tissues of lactating white mice]. / Zakonomernosti pereraspredeleniia kal'tsiia i magniia v tkaniakh laktiruiushchikh belykh myshei.

The Ca2+ and Mg2+ contents in the blood, milk and tissues involved in lactation, were studied in lactating and non-lactating albino mice. The Ca2+ concentration in the blood plasma of lactating mice was raised by 25%, and Mg2+--by 78%. The tissue concentrations of these ions did not change during lactation in muscles. The Ca2+ level was raised by 41% in the red cells in lactation, and Mg2+--by 55%; the concentration of Ca2+ and Mg2+ in the mammary alveolar tissue was respectively 4.4 and 2.9 times higher than in non-lactating animals. The data obtained suggest an interrelationship between the tissue ion content and the degree of enhancement of specific activity of the tissue during lactation.

[Blood supply and oxygen supply of localized portions of the mammary glands]. / Krovosnabzhenie i kislorodnoe obespechenie lokal'nykh uchastkov molochnoi zhelezy.

The quantitative analysis of the circulation system providing O2 transport to the mammary tissues in 34 non-lactating and 21 lactating albino mice SHR revealed that the average values of O2 tension in the alveolar complexes (43.3 +/- 14.4 torr) were 1.4 times higher and those of the blood flow (134 +/- 39 Ml/100 gxmin) 2.0-4.5 times higher than the corresponding values in the local sites of non-secreting mammary glands. Rhythmical changes of the blood flow and O2 tension revealed in the alveolar complexes, had the average period (50-55 min) corresponding to the duration of the secretory cycle. Asynchronous changes of these parameters in various local sites of the gland suggest continuous redistribution of the blood flow in the gland.

[Dynamics of blood circulation and oxygen consumption in mammary glands]. / Dinamika krovoobrashcheniia i potreblenie kisloroda v molochnoi zheleze.

In lactating albino mice, the blood flow rate and oxygen consumption in mammary tissues varied with a period of 45--50 min. The maximal values were reached at the initial stage of the secretory cycle: oxygen consumption 9.7 +/- 2.5 ml O2/100 g.min, and blood flow 94.3 +/- 21.2 ml/100 g.min. The minimal values of oxygen consumption and blood flow ere recorded on the 30--35th min of the secretory cycle and were 1.2 +/- 0.4 ml O2/100 g.min and 16.2 +/- 5.3 ml/100 g.min, respectively. Oxygen consumption by the secretory cells at the beginning of the secretory cycle averaged 19.3 +/- 5.2 ml 92/100 g.min, and within 30--35 min--3.3 +/- 1.1 ml O2/100 g.min. The linear relations between the intensity of blood flow and oxygen consumption in the mammary gland were revealed.

[Distribution of oxygen tension in breast tissues]. / Raspredelenie napriazheniia kisloroda v tkaniakh molochnoi zhelezy.

Using a mathematical model which describes the O2, transport in the alveolar cell of the mammary gland, the distribution of pO2 levels during two stages of the secretory cycle, was calculated. At the initial stage, the typical feature of which is the increased blood flow and O2 consumption, pO2 in the secretory tissue varied from 3 to 30 torr (average 9.9 torr). At the later stage of the secretory cycle characterized by the decreased blood flow and O2 consumption, pO2 levels in the secretory tissue were within the limits of 40--60 torr (average 48.9 torr). The increase of blood flow usually observed at the initial stage of the secretory cycle seems to supply tissues with the necessary amount of O2 even if the capillarization of the alveoli is minimal.