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  • 1
    Online Resource
    Online Resource
    New York, NY :Springer,
    Keywords: Heart-Molecular aspects. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (313 pages)
    Edition: 1st ed.
    ISBN: 9781461312796
    Series Statement: Developments in Molecular and Cellular Biochemistry Series ; v.18
    DDC: 612.173
    Language: English
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  • 2
    Online Resource
    Online Resource
    New York, NY :Springer,
    Keywords: Heart-Diseases-Molecular aspects. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (334 pages)
    Edition: 1st ed.
    ISBN: 9781461312895
    Series Statement: Developments in Molecular and Cellular Biochemistry Series ; v.19
    DDC: 612.1/73
    Language: English
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  • 3
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 48 (1961), S. 131-132 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4919
    Keywords: human heart ; force of contraction ; protein phosphorylation ; phospholamban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Disturbances in the cAMP production during β-adrenergic stimulation and alterations of Ca 2+ transport controlling proteins and their regulation in the sarcoplasmic reticulum might be involved in the pathogenesis of the failing human heart. Thus, we investigated the cAMP-mediated phosphorylation of phospholamban, troponin I and C-protein in electrically driven, intact isolated trabeculae carneae from nonfailing and failing (NYHA IV) human hearts in parallel to contractile properties on the same tissue samples. The increase in force of contraction induced by isoproterenol (0.2 μM) or pimobendan (100 μM), a phosphodiesterase inhibitor, was diminished in the failing human hearts compared to nonfailing hearts by 49% and 36%, respectively. Concomitantly the isoproterenol-induced phosphorylation (pmol P/mg homogenate protein) of phospholamban, troponin I and C-protein was reduced from 13.0 ± 2.4 (n = 4), 30.5 ± 1.5 (n = 5) and 11.0 ± 1.3 (n = 5) in the nonfailing heart to 5.2 ±0.6 (n = 13), 14.6 ± 2.2 (n = 16) and 7.1 ± 1.0 (n = 6) in the failing human heart, respectively. Pimobendan changed the phosphorylation state of these proteins similar to isoproterenol. The fact that combined addition of both agents or dibuturyl CAMP (1 mM) alone restored the phosphorylation capacity as observed in the control groups indicates that i) a reduced cAMP generation is related to the reduced phosphorylation of regulatory phosphoproteins located in the sarcoplasmic reticulum and contractile apparatus e.g. phospholamban, troponin I and C-protein, that ii) there is a relationship between protein phosphorylation state and contractile activity and that iii) no changes in the respective content of phosphoproteins are involved in the limitation of cAMP-mediated inotopic activity in the failing human heart. (Mol Cell Biochem 157: 171–179, 1996)
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 31-38 
    ISSN: 1573-4919
    Keywords: developing heart ; G proteins ; adenylyl cyclase ; phosphoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The postnatal alterations of the composition of a subunit isoforms (Giαc, G iα3 Goα, and Gqα of G proteins, the adenylyl cyclase activity as well as of cAMP-regulated phosphoproteins e.g. troponin and phospholamban were investigated in the ventricular tissue of 1, 7, 30 days old rats. Quantitative immunodetection revealed a 5.7-fold decrease in Giα3 at 30th postnatal day compared with the postnatal day 1 and up to 15-fold at 4 months. The amounts of Gqα and G∞ as well as the Gα subunits were found to be higher in the earlier life period compared to the adult. In contrast, the content of Gsα was uneffected by the developmental state. Basal adenylyl cyclase activity (pmoles cAMP/min × mg protein) increased from 30.9 ± 5.0, 36.8 ± 5.0 to 63.9 ± 5.9 at 1st, 7th and 30th postnatal day, respectively. Isoprenaline (100 μM) enhanced the activity of adenylyl cyclase from day 1, 7–30 from 46.2 ± 7.0, 79.1 ± 9.2 to 120.5 ± 7.2, respectively. The effects of forskolin and NaF on adenylyl cyclase activity was found to be not influenced within the first postnatal month. Furthermore, a developmentally controlled expression of cardiac troponin I was observed (6-fold from the first to the 28th postnatal day) whereas the level of phospholamban was found to be age-independent. In conclusion, there is an increase in the efficiency of the β-adrenergic signal transfer mainly caused by a reduction of the inhibitiory G proteins and a dominance of the Gsα-linked pathway in the postnatal rat heart. Furthermore the developmentally controlled expression of troponin I might be of functional importance in the cAMP-supported relaxation. Additionally, altered Gqα, Goα and Gβ pattern of the developing rat ventricle may play a role in the observed change of α-adrenerg-mediated heart contractility as well as in cardiac differentiation and growth processes.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4919
    Keywords: cardiac cycle ; cyclic AMP ; protein kinase activation ; propranolol ; cryobiopsy technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Oscillation of cyclic AMP and in the activity ratio of cyclic AMP-dependent protein kinase and of glycogen phosphorylase with the cardiac cycle were demonstrated in the canine heart in situ. For tissue sampling an ECG (R-wave)-triggered, automatically working push-freeze-drill apparatus was developed which allows intraventricular cryobiopsies from the left ventricular muscle of anaesthetized open-chest dogs. The nucleotide cyclic AMP oscillated with the cardiac cycle during normal working condition, the higher cyclic AMP level occuring during systole. Cyclic GMP was assayed to be without oscillatory changes during the contraction-relaxation cycle. The rise in the activity ratio of protein kinase was found to coincide with the maximum in the level of cyclic AMP. Propranolol pretreatment prevents the transient in the level of the nucleotide as well as in the activity ratio of the kinase indicating i) a causal relationship between these changes and ii) a neurohumoral, beat-to-beat regulation by catecholamines released from the sympathetic nerve endings within the heart. Contrary the activity ratio of phosphorylase retains its transient changes during the cardiac cycle in the presence of propranolol, indicating a Ca-mediated activation of phosphorlase kinase during the contraction process.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4919
    Keywords: myocardial infarction ; glycogen phosphorylase ; isoenzyme BB ; glycogenolysis ; enzyme release ; glycogen-glycogenolysis-complex ; cardiac ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This review deals with glycogen phosphorylase (GP) and its isoenzyme BB in the diagnosis of ischaemic myocardial injury. Early identification and confirmation of acute myocardial infarction is essential for correct patient care and disposition decision in the emergency department. In this respect, glycogen phosphorylase isoenzyme BB (GPBB) based on its metabolic function is an enzyme for early laboratory detection of ischaemia. In the aerobic heart muscle GPBB together with glycogen is tightly associated with the vesicles of the sarcoplasmic reticulum. Release of GPBB, the main isoform in the human myocardium, essentially depends on the degradation of glycogen, which is catalyzed by GP. Ischaemia is known to favour the conversion of bound GP in the b form into GP a, thereby accelerating glycogen breakdown, which is the ultimate prerequisite for getting GP into a soluble form being able to move freely in the cytosol. The efflux of GPBB into the extracellular fluid follows if ischaemia-induced structural alterations in the cell membrane become manifest. The clinical application of GPBB as a marker of ischaemic myocardial injury is a very promising tool for extending our knowledge of the severity of myocardial ischaemic events in the various coronary syndromes. The rational roots of this development were originated from Albert Wollenberger's research work on the biochemistry of cardiac ischaemia and the transient acceleration of glycogenolysis mainly brought about by GP activation.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4919
    Keywords: stress protein induction ; HSP25 ; intracellular location ; isolated perfused heart ; hyperthermia ; contractile function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Recent investigations concentrate on the correlation between the myocardial expression of the inducible 70-kDa heat shock protein (HSP70i) by different stress conditions and its possible protective effects. Only few studies have focused on the involvement of small heat shock proteins in this process. We analyzed the location of the small heat shock protein HSP25 in isolated cardiomyocytes as well as its location and induction in isolated perfused hearts of rats. By immunofluorescence microscopy HSP25 was found to colocalize with actin in the I-band of myofibrils in cardiomyocytes of isolated perfused hearts as well as in isolated neonatal and adult cardiomyocytes. Hyperthermic perfusion of isolated hearts for 45 min resulted in modulation of different parameters of heart function and in induction of HSP25 and HSP70i. Temperatures higher than 43°C (44–46°C) were lethal with respect to the contractile function of the hearts. Compared to control hearts perfused at 37°C, significant increases during hyperthermic perfusion at 42°C and 43°C were obtained for heart rate, contraction velocity and relaxation velocity. In response to hyperthermia at 43°C and after subsequent normothermic perfusion for 135 min at 37°C, left ventricular pressure, contraction velocity and relaxation velocity remained significantly elevated. However, heart rate returned to control values immediately after the period of heat treatment. HSP25 is constitutively expressed even in normothermic perfused hearts as shown by Western blotting. Hyperthermia increased the content of HSP25 only in the left ventricular tissue. In contrast, HSP70i was strongly induced in all analyzed parts of the myocardium (left ventricle, right ventricle, septum). Our findings suggest a differential regulation of HSP25 and HSP70i expression in response to hyperthermia in isolated perfused hearts. The constitutively expressed HSP25 seems to be located adjacent to the myofibrils which implies a specific role of this protein even under unstressed conditions for the contractile function of the myocardium.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 160-161 (1996), S. 1-1 
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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