[Regularities of resumption and metabolic maintenance of estrus cycles in domestic ruminants].

The review summarizes information from literature and results of author's own investigation concerning regularities of estrus cycles resumption and conditions of metabolic maintenances of estrus cyclicity in cows. It discusses problems of lenghtening of the anoestrus interval, alteration of cyclicity rhythm and normal estrus cycles resumption in domestic ruminant during first months of lactating period.

[Effect of motor activity of different intensity upon the blood composition and respiratory function in domestic animals during their first months of life].

Responses of the blood content, breathing function and gaseous metabolism to changes of motional activity level in calves in the first 30 days of a postnatal period were investigated. Keeping of calves in conditions natural for mature animals at different motor activity levels as compared with the locomotion limitation leads to a lesser reduction of hemoglobin content, haematocrit ratio, red cells and reticulocytes count in blood of calves during first 30 days of life. In comparison with calves with additional motor activity, 10-day old calves with natural motor activity and locomotion limitation showed an increase of the protein level and reduction of glucose and cholesterol in the blood. Locomotion limitation of calves during the first 30 days of postnatal period caused reduction of the blood oxygen carrying capacity (erythrocytes and reticulocytes count) with simultaneous decrease of breathing function and gaseous metabolism efficiency (breathing output, minute ventilation, carbon dioxide output and oxygen uptake).

[Dependence of Na, K-ATPase enzyme activity on the surface properties and charge of the substances interacting with the cell membrane]. / Zavisimost' fermentativnoi aktivnosti Na, K-ATFazy ot poverkhnostnykh svoistv i zariada vzaimodeistvuiushchikh s kletochnoi membranoi veshchestv.

The surface activity and effect of histone, sodium deoxycholate and Triton X-100 on N+,K+-ATPase have been compared. It has been found that the coefficient of surface tightness on the borderline of suspension of ATPase containing membranes/air decreases with the increase in concentrations of these agents. The enzyme activity undergoes biphasic modification increasing with lower and decreasing with higher concentrations of the agents. The effectiveness of the agents depends on the charge of their molecules. The mechanism of interaction between Na+,K+-ATPase and the above modifiers is discussed.

[Effect of pH on ATPase activity and 18-O metabolism catalyzed by membrane preparations of Na,K-ATPase from guinea pig kidneys]. / Vliianie pH na ATFaznuiu aktivnost' i 180-obmen, kataliziruemye membrannymi preparatami na,K-ATPazy iz pochek morskoi svinki.

The effect of pH in the incubation medium on ATPase activity and the direct 18O-exchange, catalyzed by initial and treated by surface active agents membrane preparations of Na, K-ATPase has been studied. The pH dependence of the ratio between the direct 18O exchange and Na,K-ATPase activity was detected; this ratio being equal to 4,5 +/- +/- 0.6, 1.5 +/- 0.1 and 0.4 +/- 0.1 at the pH values of 6.1, 7.5 and 9.0, respectively. The pretreatment of preparations by DOC or histone H2a, used in both activatory and inhibitory-amounts, abolished the effect of acid pH and made the ratio practically the same at 6.1 and 7.5 pH values. Both agents did not affect the action of the alcaline pH value equal to 9.0. Triton X-100 was not able to change the pH dependence of the ratio.

[Effect of surface-active agents on Na, K-ATPase from guinea pig kidneys]. / Vliianie poverkhnostno-aktivnykh veshchestv na Na, K-ATFazu iz pochek morskoi svinki.

The effect of surface active agents on the activity of Na, K-ATPase and on the direct medium 18O exchange in the membrane preparations of the guinea pig kidney has been studied. The medium 18O exchange was considered as a character of the K+-dependent stage in ATPase reaction. Low concentration of all the surface active agents were shown to stimulate, and high concentrations -- to inhibit both ATPase and medium 18O exchange. The relation between medium 18O exchange and Na,K-ATPase activity was found to be equal to 1.5 +/- 0.1. The treatment of preparations by activating amounts of the surface active agents resulted in lowering this relation up to 1.0 +/- 0.09 and 1.3 +/- 0.04 for DOC and triton X-100, correspondently, due to a stronger stimulation of ATPase activity than of medium 18O exchange. With the inhibiting amounts of triton X-100 and histone H2a, this relation did not change, but it decreased in the presence of equal amounts of DOC.