Succinate dehydrogenase activity in various parts of the rat heart in systole and diastole

After fixation of the rat heart at the state of systole and diastole, succinate dehydrogenase (SDH) activity has been revealed. In distributions of the muscle fibers according to their optic density, statistic characteristics connected with the first four moments have been taken into consideration. SDH activity is different in five cardiac parts. Individual changeability is more pronounced in the all cardiac parts at diastole. In comparison to the internal one at systole, it is lower in the all parts, and at diastole--in the atria only. The ratio of the internal and individual changeability is in such a state, that it should be taken into account in all statistical calculations, connected with SDH activity determination in cardiomyocytes.     

Succinate dehydrogenase activity in rat dorsolateral ventral horn motoneurons at L6 after spaceflight and recovery

Succinate dehydrogenase (SDH) activity levels of motoneurons in the rostral, middle, and caudal portions of the dorsolateral region of the ventral horn of the 6th lumbar (L6) segment of the rat spinal cord were determined after 14 days of spaceflight and after 9 days of recovery on Earth. The mean SDH activity of motoneurons with cell body sizes between 500 and 800 micrometers2 located in the rostral portion of the L6 segment was lower in spaceflight than in age-matched control rats. The decrease in motoneuron SDH activity persisted for at least 9 days of recovery on Earth. In contrast, the mean SDH activity of motoneurons located in the middle and caudal portions of the L6 segment were unaffected by spaceflight and recovery on Earth. The motoneurons in the rostral portion of the L6 segment presumably innervate both high- and low-oxidative fibers in hindlimb muscles, whereas those in the middle and caudal portions presumably innervate perineal muscles that are comprised only of low-oxidative fibers. These data indicate that moderate-sized motoneurons, most likely innervating fibers in high-oxidative muscles, are responsive to the microgravity environment.     

Succinate dehydrogenase activity in the wall of rabbit aorta

Summary An investigation of succinate dehydrogenase activity in the wall of rabbit aorta was carried out. The level of succinate dehydrogenase per se in the smooth muscle cells was found to be fairly high, while the mitochondrial level of carrier CoQ was low. The latter may explain the low level or lack of activity of succinate dehydrogenase in these cells as noticed by previous authors.A reliable image of the actual level of succinate dehydrogenase was obtained only by adding CoQ₁₀ to the incubation system. PMS should be avoided, as it induced a Nothing dehydrogenase reaction even at low concentrations.     

Immunocompetent cells in the beds of full-thickness skin allografts transplanted at various times of the day

The number of lymphocytes, immunoblasts, plasmoblasts and plasmocytes was counted in the tissues of the couch of the skin grafts transplanted at 8 a. m., 4 and 24 p. m. Sixty-six, 76 and 86 hours after operation the differences were significant in the number of lymphocytes and plasmocytes, whereas after 136, 146 and 156 hours in the quantity of all cells under study. This indicates the influence of the circadian phase of the body on the course and intensity of cell and tissue reactions seen during graft rejection. A preliminary conclusion is drawn that 8 a. m. is a less favourable time for performing skin allotransplantation in mice, whereas 4 p. m. is a more favorable time.     

Succinate dehydrogenase activity in rat kidney after repeated administrations of p-aminohippurate or sodium chloride

During PAH excretion and 18 h after repeated PAH administrations to rats, renal cortical SDH activity was unchanged in comparison with untreated controls. On the other hand, 18 h after repeated administrations of 0.9% or 1.8% NaCl solution, SDH activity was decreased by about 20% in kidney cortex. In outer medulla SDH activity was decreased 18 h after all pretreatments. The decline of SDH activity was observed whenever an increased urinary Na excretion occurred, except that PAH was repeatedly administered. The probability is discussed that substrate-induced stimulation of the carrier system for weak organic acids is accompanied by an increase of mitochondrial activity in kidney cortex.     

Proliferative activity of the hepatocytes at different times of day during prolonged hypokinesia

The white male Wistar rats were exposed to hypokinesia during 10 days. Essential oppression of the mitotic division of hepatocytes in the rats' liver at the hypokinesia was revealed. The cellular division was exposed to the daily oscillations. The quantity of mitoses prevailed in the day and evening. In these conditions the quantity of binucleate cells increased as compared with the control. The deficit of mitoses stipulates the delay of postnatal weight of liver at the hypokinesia. Binucleate hepatocytes are the analog of the polyploid cells and their large population compensates for the increased organism's need in liver function in the experiment.     

Succinate dehydrogenase activity of Escherichia coli cells after heat stress and during the reparative process

The resting cells of different E. coli cells remained viable after their heating at 48 degrees C for 30 min. The activity of their succinate dehydrogenase (SDH) (EC 1.3.99.1) was not more than 50% of the control one. When the cells were inoculated after a heat stress into a peptone medium, they started to grow at a high rate. However, their maximal specific growth rate mu and the overall biomass yield were less than in the control. The SDH activity of the cells reached the original level by the end of the logarithmic growth phase. This did not happen when the cells were incubated in 0.14 M NaCl for a time necessary for the culture to reach the end of the logarithmic growth phase. The SDH activity (in absolute values) of cell-free extracts was not greater than 35% of the cell SDH activity. The SDH activity of the cell-free extracts did not change after their heating at 48 degrees C. The SDH activity of E. coli cells is recommended to be used as a parameter indicative of their stress state.     

Surface-active properties of pulmonary surfactant and the functional activity of type II alveolocytes at various times of the day under experimental conditions

Complex examination of lungs in 24 healthy guinea pigs in different periods of day using physicochemical, biochemical and electron-microscopic methods has revealed that the highest surface activity of the pulmonary surfactant (PS) is observed in the evening and at night, as phospholipids contain the highest amount of a surfactant of the phosphatidylcholine fraction the most active in the surface-active respect. An increase in the content of PS phospholipids in this period of the day appears to be a consequence of synthesis and secretion intensification in the second-type alveolocytes, that may be due to an increased effect of the vagus nerve.