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  • sarcoplasmic reticulum  (3)
  • Plasma renin concentration  (2)
  • Temperature adaptation  (2)
  • Springer  (7)
  • American Heart Association (AHA)
  • National Academy of Sciences
  • 2010-2014
  • 1995-1999  (5)
  • 1970-1974  (2)
  • 1955-1959
Document type
Keywords
Publisher
  • Springer  (7)
  • American Heart Association (AHA)
  • National Academy of Sciences
Years
  • 2010-2014
  • 1995-1999  (5)
  • 1970-1974  (2)
  • 1955-1959
  • 1985-1989  (1)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Bestimmung der Plasma-Renin-Konzentration mittels Radioimmunoassays für Angiotensin I (1972)
    Springer
    Journal of molecular medicine 50 (1972), S. 702-705 
    Details
    ISSN: 1432-1440
    Keywords: Plasma renin concentration ; radioimmunoassay ; angiotensin I ; Plasma-Renin-Konzentration ; radioimmunologischer Nachweis ; Angiotensin I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ein Radioimmunoassay für Angiotensin I und seine Anwendung für die Messung der Reninkonzentration im Plasma werden beschrieben. Die zur Herstellung von Angiotensinantikörpern und radioaktiv markiertem Angiotensin sowie zur Trennung von gebundenem und freiem Hormon benutzten Verfahren werden mitgeteilt. Die Empfindlichkeit der Methode erlaubt den Nachweis von zwanzig Pikogramm Angiotensin I. Zur Messung der Reninkonzentration wurde substratfreies Plasma mit Schafsubstrat im Überschuß versetzt und in Anwesenheit von Inhibitoren von „converting enzyme“ und Angiotensinasen bei 37°C inkubiert. Das gebildete Angiotensin wurde in 20 µl des proteinfreien Inkubationsgemisches bestimmt. Die initiale Geschwindigkeit der Angiotensinbildung wurde zur Berechnung der Reninkonzentration herangezogen. Als eine Einheit wurde die Reninmenge definiert, die ein Nanogramm Angiotensin I pro Stunde Inkubation bildet. Normalwerte unter kontrollierter natriumreicher und natriumarmer Diät wurden ermittelt. Die Empfindlichkeit der Methode erlaubt die Messung der Reninkonzentration im Plasma von Patienten mit primärem Aldosteronismus.
    Notes: Summary A radioimmunoassay for angiotensin I and its application to the measurement of plasma renin concentration are described. Outlined are the methods which were used to elicite antibodies against angiotensin I, to iodinate angiotensin I with iodine125, and to separate free from antibody-bound hormone. The method is sensitive enough to detect 20 picogrammes of angiotensin I. Substrate-free plasma was mixed with excess of sheep substrate. The mixture was incubated at 37°C in the presence of inhibitors of converting enzyme and angiotensinases. The generated angiotensin I was measured in 20 µl of the protein-free incubation mixture. The initial velocity of angiotensin generation was used to calculate the renin concentration. One unit was defined as the amount of renin which generates one nanogram of angiotensin per hour. Normal values of plasma renin concentration were obtained both during sodium loading and sodium depletion. The sensitivity of the method allows the measurement of plasma renin in patients with primary aldosteronism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01495529
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  • 2
    Electronic Resource
    Electronic Resource
    Die Plasma-Renin-Konzentration beim primären Hyperaldosteronismus unter Suppressions- und Stimulationsbedingungen (1972)
    Springer
    Journal of molecular medicine 50 (1972), S. 783-786 
    Details
    ISSN: 1432-1440
    Keywords: Primary aldosteronism ; Plasma renin concentration ; Primärer Hyperaldosteronismus ; Plasma-Renin-Konzentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 13 Patienten mit einem primären Hyperaldosteronismus wurde die Plasma-Renin-Konzentration unter Stimulations- und unter Suppressionsbedingungen gemessen. Eine hochempfindliche Methode zur Reninmessung, die sich eines Radioimmunoassays für Angiotensin I bediente, wurde verwandt. Bei jedem der Patienten ließ sich die Reninkonzentration im Plasma gut messen. Die Werte lagen hochsignifikant unter den Normbereichen, die unter denselben Bedingungen ermittelt worden waren. Am eindrücklichsten war der Unterschied zwischen normalen und pathologischen Werten unter Stimulationsbedingungen. Nach Kochsalzentzug stieg die Reninkonzentration zwar bei nahezu allen Patienten signifikant an, der Anstieg war jedoch subnormal, gemessen an dem gesunden Kontrollkollektiv. Renin ist auch beim primären Aldosteronismus im Plasma vorhanden und reagiert auf Stimulation qualitativ regelrecht, quantitativ jedoch subnormal.
    Notes: Summary Plasma renin concentration (PRC) was measured in thirteen patients with primary aldosteronism during high and low sodium intake. A highly sensitive method using a radioimmunoassay for angiotensin I was applied for the determinations of PRC. PRC was detectable in each patient. The values obtained were significantly lower than the normal ranges which were assessed under the same conditions. Most impressive was the difference between normal and pathological values during sodium deprivation. PRC rose in almost each patient after several days of dietary sodium restriction. The increase was subnormal, however, when compared with normal controls. Renin is present in plasma of patients with primary aldosteronism. It responds qualitatively normally, but quantitatively subnormally when stimulated by sodium deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01490305
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes (1998)
    Springer
    Molecular and cellular biochemistry 188 (1998), S. 177-185 
    Details
    ISSN: 1573-4919
    Keywords: neonatal rat cardiomyocyte culture ; sarcoplasmic reticulum ; phospholamban ; calcium ATPase ; calcium transport ; thyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This study investigates sarcoplasmic reticulum (SR) calcium-(Ca2+) transport ATPase (SERCA2a) and phospholamban (PLB) in cultured spontaneously contracting neonatal rat cardiomyocytes (CM) to ascertain the function of both SR proteins under various culture conditions. The two major SR proteins were readily detectable in cultured CM by immunofluorescent microscopy using specific anti-SERCA2 and anti-PLB antibodies. Double labeling technique revealed that PLB-positive CM also labeled with anti-SERCA2. Coexpression of SERCA2 and PLB in CM was supported by measurement of cell homogenate oxalate-supported Ca2+ uptake which was completely inhibited by thapsigargin and stimulated by protein kinase A-catalyzed phosphorylation. Under serum-free conditions, incubation of CM with the SERCA2a expression modulator 3,3′,5-triiodo-L-thyronine (100 nM, 72 h) resulted in elevated Ca2+ uptake of +33%. Specific Ca2+ uptake activity was not altered if insulin was omitted from the serum-free culture medium but total SR Ca2+ transport activity was reduced under this culture condition. The results indicate that primary culture of spontaneously contracting neonatal rat CM can be employed as a useful model system for investigating both short- and long-term mechanisms determining the Ca2+ re-uptake function of the SR under defined culture conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006850724830
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  • 4
    Electronic Resource
    Electronic Resource
    Early postnatal changes in sarcoplasmic reticulum calcium transport function in spontaneously hypertensive rats (1996)
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 57-66 
    Details
    ISSN: 1573-4919
    Keywords: heart ; postnatal development ; sarcoplasmic reticulum ; phospholamban ; calcium transport ; spontaneously hypertensive rats ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This comparative study investigates the relationship between sarcoplasmic reticulum (SR) calcium(Ca2+)-ATPase transport activity and phospholamban (PLB) phosphorylation in whole cardiac homogenates of spo`ntaneously hypertensive rats (SHR) and their parent, normotensive Wistar Kyoto (WKY) strain during early postnatal development at days 1, 3, 6, 12 and at day 40 to ascertain any difference in SR Ca2+ handling before the onset of hypertension. At day 1, the rate of homogenate oxalate-supported Ca2+ uptake was significantly higher in SHR than in WKY (0.25 ± 0.02 vs 0.12 ± 0.01 nmoles Ca2+/mg wet ventricular weight/min, respectively; p 〈 0.001). This interstrain difference disappeared with further developmental increase in SR Ca2+ transport. Western Blot analysis and a semiquantitative ELISA did not reveal any difference in the amount of immunoreactive PLB (per mg of total tissue protein) between strains at any of the ages studied. In addition, levels of phosphorylated PLB formed in vitro in the presence of radiolabelled ATP and catalytic (C) subunit of protein kinase A did not differ between SHR and WKY at days 1, 3, 6 and 12. At day 40, C subunit-catalyzed formation of 32P-PLB was reduced by 66% (p 〈 0.001) in SHR when compared to age-matched WKY In the early postnatal period between day 1 and 12 SR Ca2+-transport values were linearly related to the respective 32P-PLB levels of both SHR and WKY rats. The results indicate that cardiac SR of SHR can sequester Ca2+ at a much higher rate immediately after birth compared to WKY rats. The disappearance of this interstrain difference with further development suggests that some endogenous neuroendocrine or nutritional factor(s) from the hypertensive mother may exert an influence upon the developing heart in utero resulting in a transiently advanced maturation of the SR Ca2+ transport function in SHR pups at the time of birth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408641
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanisms of thyroid hormone control over sensitivity and maximal contractile responsiveness to β-adrenergic agonists in atria (1998)
    Springer
    Molecular and cellular biochemistry 184 (1998), S. 419-426 
    Details
    ISSN: 1573-4919
    Keywords: atria ; thyroid hormones ; β-adrenergic effect ; sarcoplasmic reticulum ; phospholamban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This paper discusses the mechanisms of two basic effects of thyroid hormones on atrial responses to β-adrenergic agonists, i.e. increased inotropic sensitivity and decreased maximal contractile responsiveness. The increased sensitivity of atria to β-adrenergic agonists under thyroid hormones appears to be related to increases in β-adrenoceptor density and Gs/Gi protein ratio, leading to activation of Gs-mediated pathway, but suppression of Gi-mediated pathway of adenylate cyclase regulation. Therefore, the i/c concentrations of cAMP and corresponding inotropic responses achieve their maximums at lower doses of β-adrenergic agonist. Thyroid hormones also decrease the expression of phospholamban, but increase the expression of sarcoplasmic reticulum Ca+2-pump. As a result, the basal activity of sarcoplasmic reticulum Ca+2-pump increases, but its β-adrenergic activation through phosphorylation of phospholamban decreases. It is suggested that these changes are causal for decreased maximal inotropic and lusitropic responses of atria to β-adrenergic agonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006835213108
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  • 6
    Electronic Resource
    Electronic Resource
    Ecophysiological studies on citrate-synthase: (I) enzyme regulation of selected crustaceans with regard to temperature adaptation (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 46-55 
    Details
    ISSN: 1432-136X
    Keywords: Citrate synthase ; Enzyme characteristics ; Temperature adaptation ; Isopod crustacea ; Euphausiid crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The characteristics and properties chromatographically purified citrate synthase from the euphausiids Euphausia superba (Antarctica) and Meganyctiphanes norvegica (Scandinavian Kattegat and Mediterranean Sea) and from the isopods Serolis polita (Antarctica) and Idotea baltica (Baltic Sea) were used to elucidate biochemical mechanisms of temperature adaptation. Additionally, maintenance experiments were carried out on the euphausiids to determine mechanisms of short term acclimation. Temperature optima (between 37 and 45°C) were unrelated to genotypic cold adaptation, but the activation energy of the Antarctic krill E. superba (10.9 kJ · mol-1) was only a quarter of that in other species (41.8–45.1 kJ · mol-1). The minima of apparent Michaelis constants (total range: 4–20 μmol · 1-1 oxaloacetate; 7–45 μmol · 1-1 acetyl-coenzyme A) showed no relation to natural conditions, and no distinct pH optimum occurred at ambient temperatures. In contrast, apparent Michaelis constants and specific enzyme activities were related to maintenance temperatures in M. norvegica, but not in E. superba. The differences between M. norvegica and E. superba can be interpreted as adaptations to the changes in ambient temperature with regard to the respective steno- and eurythermic tolerances of these crustaceans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264685
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  • 7
    Electronic Resource
    Electronic Resource
    Ecophysiological studies on citrate synthase: (II) enzyme regulation of selected crustaceans with regard to life-style and the climatic zone (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 56-61 
    Details
    ISSN: 1432-136X
    Keywords: Citrate synthase ; Enzyme regulation ; Temperature adaptation ; ATP inhibition ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Citrate synthase is a regulatory enzyme of the energy metabolism pathway controlling the citric acid cycle. It was studied in order to determine modes of enzyme regulation with regard to the life-style of the investigated species. Citrate synthase from crustaceans with different life-styles were compared: the pelagic euphausiids Euphausia superba from the Antarctic and Meganyctiphanes norvegica from the Scandinavian Kattegat and the Mediterranean were compared to the benthic isopods Serolis polita from the Antarctic and Idotea baltica from the Baltic. Citrate synthase was partly purified chromatographically and the influence of adenosine 5′-triphosphate on enzyme activity was examined. Mechanisms of inhibition and inhibitor constants were determined. Two different mechanisms of enzyme regulation by ATP were found. Citrate synthase from isopods was only competitively inhibited, while citrate synthase from euphausiids showed not only competitive inhibition but also activation by low concentrations of ATP. This activation is equivalent to the reversed methanism of uncompetitive inhibition. The ecophysiological relevances of the coupling of these mechanisms are discussed. The degree of competitive inhibition was different in the two groups of investigated crustaceans. Inhibitor constants were similar within the euphausiids but not in isopods, which showed higher or lower inhibition depending on the climatic zone: the colder the ambient temperature the lower the ATP inhibition. A possible mechanism of temperature adaptation through effects of varying inhibition constants is concluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264686
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