Electron-cytochemical study of ATP-ase activity in the brain after death]

The lead method was applied to determine the localization of the ATP-asic activity in the rat and human brains at different periods after death. This activity was revealed in the cytoplasm of the cells, chromatin and the nucleolus, and also in the synaptic terminals. In the vascular capillaries the product of reaction was localized in the basal layer and on the cytomembrane of the endothelial cells. The results obtained pointed to a good preservation of the ATP-asic activity in the postmortem brain.     

Effects of hypothermia on ATPase activity in the cerebral tissue of rats]

The hypothermia 20 degrees C of various periods of action stimulates greatly the activity of Na,K-ATF-ase and causes some insignificant changes in the process of Mg-ATF-ase in homogenates, synaptosomal and mitochondrial fractions, extracted from cortex of big hemispheres. The gained data testifies to some differences of the properties of membrane while cooling.     

Properties and localization of bicarbonate-stimulated ATPase activity in rat brain

Abstract— A 20–30 per cent stimulation of ATPase activity by added NaHCO₃ was found in homogenates of a variety of mammalian tissues. The subcellular distribution of this (HCO₃^-)—stimulated activity was examined in detail using rat cerebral cortex. The stimulation was specific for the HCO₃^- ion and was predominantly localized in the mitochondrial subcellular fraction, in which a 2-fold stimulation by HCO₃^- was found. The effect of inhibitors supported the identification as the mitochondrial ATPase. Both sodium azide and thiocyanate were inhibitory. The effects of varying the Mg²⁺ concentration, HCO₃^- concentration, and pH were also studied. In the presence of HCO₃^- the K_m for ATP was reduced approximately 3-fold. There was no effect of HCO₃^- on the ma + K) ATPase or Mg²⁺ ATPase from the microsomal fraction of rat cerebral cortex. Our findings have been discussed in relation to previous work on HCO₃^- stimulation of ATPae activity in subcellular fractions from other tissues, as well as its possible relevance to the known effects of HCO₃^- and carbonic anhydrase on active ion transport.     

Electron-cytochemical and morphometric study of the activity of several enzymes in thyrocyte metochondria during malignant degeneration]

Cytochrome oxidase and succinic dehydrogenase activities were studied in the mitochondria of rat thyroid cell during experimental malignization by means of the electron-cytochemical and morphometric methods. The activity of these enzymes in the mitochondria changed depending on the stage of malignization: at the early stages it approached the normal activity, and at the later stages (precancer)--it decreased and approached the mitochondrial activity of cancer cells. A sharp decrease in the activity of the enzymes under study in the morphologically changed mitochondria of cancer cells may characterize their qualitative changes.     

Effect of adrenaline on the ATPase activity of suslik brain synaptosomes]

Action of adrenaline on ATPase activity of ground squirrel synaptosomes in vitro at 37 degrees and 17 degrees C was studied. It has been shown in experiments in vitro at 37 degrees C that adrenaline in a concentration of 5.10(-4) M influenced Mg and Na, K-ATPase of the synaptosomes in ground squirrel brain. The inhibition (42-72%) of Na, K-ATPase in the synaptosomes of the brain was seen during hibernation and in summer. The inhibition of Mg-ATPase (50%) was observed only in summer. The effect of adrenaline on the activity of Na, K-ATPase of synaptosome was seen in vitro as well as at 17 degrees (a 50% inhibition). It was shown that adrenaline in vitro at a concentration of 5.10(-4) M inhibited ATPases more than noradrenaline.     

A new method for determination of ATPase activity in tissue homogenates]

Authors describe a new method to determine Mg2+ and Na+K+ATPase activity on extremely small samples of tissue homogenates. They use specific inhibitors to discern between the two activities and a sensitive colorimetric method to dose Pi released from ATP, Lower limit of sensitivity is about 0,0100 micromoles of Pi/mg proteins/hour.     

The localization of the anion-sensitive ATPase activity in corneal endothelium

The localization of the anion-sensitive ATPase (EC 3.6.1.3) of bovine corneal endothelium has been investigated. Homogenates were fractionated by differential and density gradient centrifugation, into fractions enriched in plasma membranes and mitochondria. (Na+ + K+)-ATPase (EC 3.6.1.3) and cytochrome oxidase (EC 1.9.3.1) were used as marker enzymes for these two cell components, and glucose-6-phosphatase (EC 3.1.3.5) was used to identify endoplasmic reticulum. 5'-Nucleotidase (EC 3.1.3.5) was also measured but was found not to be exclusively associated with any one cell component. The activity of the anion-sensitive ATPase (HCO3--ATPase) was measured in suspensions that were frozen and thawed before assay in order to expose latent enzyme activity. The fraction containing the greatest amount of (Na+ + K+)-ATPase (35%) contained only 6% of the cytochrome oxidase and HCO3--ATPase. Conversely, the mitochondrial fraction, containing 40% of the cytochrome oxidase, contained about 40% of the HCO3--ATPase, but only 7% of the (Na+ + K+)-ATPase. The recoveries and relative degree of purification of the cytochrome oxidase and HCO3--ATPase were also nearly identical in the other fractions examined. It was concluded that the anion-sensitive ATPase activity of the corneal endothelium is located solely in the mitochondria and not in the plasma membrane. Consequently, any role that the enzymes may have in the transport of bicarbonate across this tissue, which had been suggested in earlier studies, must be an indirect one.     

Ultrastructural localization study of two Wolfgram proteins in rat brain tissue

Brain Cell Biology - The ultrastructural immunohistochemical localization of Wolfgram proteins W1 and W2 is described in young rat brain tissue. The labelling by the antiserum to W1 is restricted...     

Protein kinase C activity in the brain tissue of spontaneously hypertensive rats

Protein kinase C activities in the brain tissue of spontaneously hypertensive rats (SHR) and normotensive control rats (WKY) were studied. Protein kinase C activity in SHR was found to be 35% higher than that in normotensive control rats. It is suggested that the increase in protein kinase C activity is involved in the mechanism of membrane alterations in primary hypertension.     

Lipoprotein lipase activity in white adipose tissue of rats subjected to exercise--rest cycles

This study was conducted to determine serum lipid levels and the activity of lipoprotein lipase in epididymal white adipose tissue of rats undergoing exercise training. During the 8-week period of treatment, one group of rats was kept sedentary and the remaining animals were exercise trained either continually (1 h of daily treadmill running) or intermittently (alternate weeks of daily running and inactivity). Exercise training, either continual or intermittent, decreased postprandial serum total and high-density lipoprotein cholesterol concentrations, which returned to sedentary levels in the intermittently trained animals following a week of rest. Lipoprotein lipase activity in whole epididymal adipose pad was lower in rats trained continually than in the sedentary group at the end of the treatment. The intermittent training program elicited large fluctuations in both the specific (per milligram of protein) and total (per tissue) activity of lipoprotein lipase in white adipose tissue. During rest periods, enzyme activity rose to levels that were higher than those of sedentary rats, whereas lipase activity was below that of sedentary animals following a week of running. In the last exercise--rest cycle, body weight gain of the intermittently trained rats was nearly abolished during the week of running, but it increased above that of sedentary animals during weeks of rest. The present results suggest that the modulation of lipoprotein lipase activity in white adipose tissue is one of the adaptations that take place to accommodate the fluctuations in the rate of energy deposition that occur in the rat during an intermittent training program.     

Effect of altitude hypoxia on ATPase activity in the brain of rats of different ages.

In experiments on 5-day-old and adult rats of both sexes, the authors investigated Na+--K+-stimulated and Mg2+-dependent ATPase activity in the cerebral cortex, subcortical formations and the medulla oblongata. They studied the effect of 20 min acute altitude hypoxia corresponding to either 7,000 or 9,000 m, in a thermostable chamber (30 degrees C). ATPase activity was found to increase during ontogenesis -- this being the greatest in cortical tissue and the least in the medulla oblongata. Hypoxia corresponding to 7,000 m altitude significantly depressed total ATPase activity in 5-day-old rats, but significantly stimulated it in adult animals. Changes in Na+--K+-stimulated ATPase activity played the major role in these changes. Hypoxia corresponding to 9,000 m altitude likewise depressed total ATPase activity in 5-day-old rats and to practically the same extent as moderate hypoxia (7,000 m). In adult rats, marked hypoxia (9,000 m) significantly reduced only Mg2+-dependent ATPase activity. Mg2+ activity rose during ontogenesis to a lesser degree than Na+--K+-stimulated ATPase and the reciprocal ratio of these ATPase and the reciprocal ratio of these ATPase activities, in the given parts of the brain, fell progressively in adult animals to values close to 1.     

Demonstration of ATPase activity in skeletal muscle fibers of the triceps muscle of arm in white rats during development

On the base of modified calcium and method from Zebe and Falk (1964) for demonstration of ATPase activity results at the long head of the triceps muscle of white rats aged 1, 3, 6 weeks and 3 month were shown. This method is proper to make visible alteration of the localisation of the reaction product during the postnatal development. Further investigations are necessary in order to correlate the steps of differentiation of muscle fibres with the strength of ATPase activity.     

The action on brain functions in white rats of the immunostimulant Freund's complete adjuvant]

The effect of immunostimulator--Freund's adjuvant complete on the nociception and learning of white rats using food-obtaining and avoidance of electric shock techniques has been studied. It has been shown that the adjuvant in doses for active immunization causes itself the expressed changes in animal behaviour. The adjuvant's injections significantly increases the learning ability of animals both with negative and positive reinforcement as compared with control one. The changes in pain severity is marked only for dose 0.2 ml. The nonspecific action of adjuvant should be taken into account in researches which use the active immunisation method.     

Dynamics of changes in the cerebral and erythrocyte ATPase activity of rats with hypoxic hypoxia]

A long-term (for 3 hours) hypoxic hypoxia was accompanied in rats by wave changes of the brain tissue Na++K+-ATPase activity. This activity decreased after a 15-minute exposure; it increased after 2 hours and fell again after a 3-hour hypoxia (decompensation period). The membrane transport enzymes of erythrocytes proved to be more resistant to hypoxia than the brain cell enzymes.