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  • Electronic Resource  (3)
  • 1990-1994
  • 1970-1974  (3)
  • 1972  (3)
  • Sympathomimetic Amines  (2)
  • DNA  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 272 (1972), S. 169-181 
    ISSN: 1432-1912
    Keywords: Embryonic Growth ; DNA ; RNA ; Nuclei
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to get insight into the synthesis rates occuring in mammalian embryos during the phase of differentiation, wet and dry weight as well as DNA-, RNA-, and nitrogen content of the whole implantation site (day 7 to 10 of gestation) and of the embryos (day 11 to 14) have been determined. Growth of the whole implantation site (day 7 to 10) proceeds almost linearly: Within a 24-h period the weight increases about 2-fold. The growth of the embryos, however, is found to be different in each 24-h period between day 8 and 14. All synthesis processes proceed at an extremely rapid rate between day 9 and 12 of gestation. The weight of embryos shows a 6-fold rise between day 11 and 12, the increase being even more pronounced on the preceding days. Growth and increase in cell mass are essentially due to cell division, since DNA content and weight change in a parallel way. Data on the nitrogen content per embryo show that the protein synthesis keeps pace with the rapid cell division. Using pure nuclear fractions isolated from 11- to 14-day-old embryos the average distribution of RNA within the cells can be estimated. The increase in the number of cells within a 24-h period is calculated from the average DNA content per embryo and the average DNA content per nucleus measured in isolated nuclei. The DNA content per nucleus of 12- to 14-day-old rat embryos is found to be almost twice (12±0.5 pg) that of diploid nuclei (6.7–7.2 pg). This inducates that a high percentage of the cells are in the late S-phase or in the G2-phase. The growth rate of the embryos between day 8 and 14 of gestation is calculated from the 24-h rate of increase in cell number which is obtained either biochemically or in the earlier stage of embryonic development with morphological studies. Some peculiarities of the duration of the cell cycle of the rapidly growing tissue are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Research in experimental medicine 158 (1972), S. 308-320 
    ISSN: 1433-8580
    Keywords: Respiratory Acidosis ; Cardiovascular Effects ; Sympathomimetic Amines ; Species Differences ; Respiratorische Acidose ; Kreislauf ; Sympathomimetica ; Speciesunterschiede
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Katzen, Hunden, Kaninchen und Hausschweinen wurden in Pentobarbitalnarkose nach Muskelrelaxation mit Alloferin® bei geschlossenem Thorax die Auswirkungen einer akuten respiratorischen Acidose auf den Kreislauf sowie dessen Reaktion auf Pharmaka untersucht. 1. BeiKatzen undSchweinen steigen in respiratorischer Acidose Herzfrequenz, dp/dtmax und Blutdruck an; beiKaninchen bleiben dp/dtmax und Blutdruck nahezu unverändert. BeiHunden hingegen sinken Schlagfrequenz, dp/dtmax und Blutdruck in Acidose ab. Untersuchungen an Katzen, die mit Reserpin vorbehandelt waren, zeigten, daß eine respiratorische Acidose einen negativ inotropen und blutdrucksenkenden Eigeneffekt besitzt. Nach Vorbehandlung mit Phenoxybenzamin verursacht eine respiratorische Acidose bei Katzen einen Blutdruckabfall sowie einen Anstieg von dp/dtmax. Nach Vorbehandlung mit Pindolol verursacht eine Acidose eine Abnahme von Frequenz und dp/dtmax, während der Blutdruck konstant bleibt. Am unvorbehandelten Tier wird der negativ inotrope Effekt einer Acidose offenbar durch eine Stimulierung des sympathischen Nervensystems überdeckt, die bei Katzen und Schweinen am ausgeprägtesten ist. 2. DieWirkung sympathomimetischer Amine auf Herz und Kreislauf ist bei allen 4 untersuchten Tierarten in Acidose abgeschwächt, wobei die Abschwächung bei den Tieren mit der stärksten sympathischen Stimulation am ausgeprägtesten ist. 3. Biochemische Untersuchungen an Hunden und Katzen ergaben, daß in Acidose K+, Mg2+, anorganisches Phosphat und Glucose im Serum ansteigen, während der Magnesiumgehalt des Herzmuskels abnimmt.
    Notes: Summary In closed chest cats, dogs, rabbits and pigs, anaesthetized with pentobarbital and relaxed with diallylnortoxiferinium dichloride the effects of a respiratory acidosis on heart and circulation as well as their reaction to sympathomimetic amines were studied. 1. Incats andpigs a respiratory acidosis causes a rise of frequency, dp/dtmax of the left ventricle and systolic blood-pressure. Inrabbits an acidosis causes no significant alteration of blood-pressure and dp/dtmax. Indogs frequency, dp/dtmax and blood-pressure decline in acidosis. In cats pretreated withreserpine a respiratory acidosis causes a negative inotropic effect and a declining of blood-pressure. After pretreating cats withphenoxybenzamine in acidosis there results a decrease of blood-pressure, but a rise of dp/dtmax and frequency; after pretreating withpindolol in acidosis dp/dtmax and frequency decline, but blood-pressure remains unaltered. 2. The effectiveness of sympathomimetic amines on heart and circulation is diminished in acidosis. This diminution is most significant in those animals (cat, pig) with the most augmented sympathetic tonus in acidosis, but experiments performed with reserpinized cats indicated that the augmented sympathetic tonus can not be the only cause for the diminished efficiency of adrenergic stimulant amines in acidosis. 3. Biochemical studies performed in acidosis showed a rise of K+, Mg2+, inorganic phosphate and glucose in serum and a decrease of Mg2+ in the heart muscle.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1912
    Keywords: Sympathomimetic Amines ; pH ; 45Calcium Uptake ; Contraction Force ; Guinea-Pig Atria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated, electrically stimulated left guinea-pig atria were incubated at 30° C in a Tyrode solution, the hydrogen ion concentration of which was varied by altering the percentage of the aerating CO2/O2-mixture. The increase of the extracellular hydrogen ion concentration from pH 8.0 to pH 7.0 caused a reduction of the 45calcium uptake and of the contraction force. The positive inotropic effect and the concomitantly occuring increased 45calcium uptake induced by isoprenaline and tyramine were markedly diminished at the lower pH, the response to tyramine being more affected by increased hydrogen ion concentration than that of isoprenaline. This is possibly due to a decrease in noradrenaline available at pH 7.0 for release by tyramine. Isoprenaline and tyramine enhanced the relative specific 45calcium activity (RSA) without altering the total tissue calcium content. On the contrary, the increase of the extracellular calcium concentration caused an augmentation of the relative specific 45calcium activity and the total tissue calcium content.
    Type of Medium: Electronic Resource
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