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  • 1
    Electronic Resource
    Electronic Resource
    Effects of Isoprenaline on Force of Contraction, cAMP Content, and Phosphorylation of Regulatory Proteins in Hearts from Chronic β-Adrenergic-Stimulated Rats (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 752 (1995), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1995.tb17430.x
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  • 2
    Electronic Resource
    Electronic Resource
    Beziehung zwischen Herzwachstum und myokardialer Kreatin- und Phosphokreatinmenge (1961)
    Springer
    Naturwissenschaften 48 (1961), S. 131-132 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00631931
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  • 3
    Electronic Resource
    Electronic Resource
    Long lasting anti-adrenergic effect of 7-oxo-prostacyclin in the heart: a cycloheximide sensitive increase of phosphodiesterase isoform I and IV activities (1994)
    Springer
    Molecular and cellular biochemistry 132 (1994), S. 57-67 
    Details
    ISSN: 1573-4919
    Keywords: heart protection ; 7-oxo-prostacyclin ; cyclic nucleotide hydrolysis ; phosphodiesterase isoenzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Evidence is accumulating that 7-oxo-prostacyclin (7-oxo-PGI2) induces a delayed indirect anti-adrenergic and cytoprotective effect on the myocardium, the mechanism of which is still unclear. To demonstrate that a single application of 7-oxo-PGI2 (50 μg/kg i.m.) 48 h prior to starting experiments attenuates the isoprenaline inducible inotropic response and accumulation of cAMP, isolated hearts of pretreated animals were perfused in the Langendorff mode with and without isoprenaline (1 to 100 nM). The late anti-adrenergic effect of the drug was manifested by a significant attenuation in the elevation of cAMP levels as well as in contractile force development. This effect was not due to changes in cAMP generation as there were identical β1-adrenoceptor densities and affinities (as calculated from [3H]-CGP binding studies), Gi and Gαs protein patterns (as taken from Western blots) as well as adenylyl cyclase activity measurements in the hearts studied. The anti-adrenergic potency of 7-oxo-PGI2, however, was found to be related to a significant rise in cyclic nucleotide hydrolysis by phosphodiesterase (PDE). Using the fast-performance liquid chromatographic separation for PDE isoforms, a significant increase in the activity of PDE isoforms I and IV (260±28 vs 110±12 pmol cGMP/min x enzyme fraction and 77±11 vs 34±3 pmol cAMP/min x enzyme fraction, respectively) was found in the solubilized fraction of cardiac membranes in comparison to untreated controls; PDE IV activity was also increased in the cytosolic fraction (106±14 vs 65±6 pmol cAMP/min x enzyme fraction). The hypothesis that the delayed anti-adrenergic effect of 7-oxo-PGI2 is initiated by an induction and accelerated synthesis of PDE I and IV in the heart is underlined by the fact that cycloheximide suppresses completely both the rise in PDE activities and the anti-adrenergic effects studied. It is suggested that an inducible predominance of cAMP degradation over its generation may be of relevance in processes related to heart protection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925675
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  • 4
    Electronic Resource
    Electronic Resource
    HSP25 in isolated perfused rat hearts: Localization and response to hyperthermia (1996)
    Springer
    Molecular and cellular biochemistry 160-161 (1996), S. 231-239 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00240054
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  • 5
    Electronic Resource
    Electronic Resource
    Preface (1996)
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 2-2 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408634
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  • 6
    Electronic Resource
    Electronic Resource
    G proteins, adenylyl cyclase and related phosphoproteins in the developing rat heart (1996)
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 31-38 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00408638
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  • 7
    Electronic Resource
    Electronic Resource
    Preface (1996)
    Springer
    Molecular and cellular biochemistry 160-161 (1996), S. 1-1 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240024
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    In-vivo phosphorylation of the cardiac L-type calcium channel beta-subunit in response to catecholamines (1996)
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 99-106 
    Details
    ISSN: 1573-4919
    Keywords: Ca2+ channels ; CAMP-dependent phosphorylation ; cardiac contractile force ; protein kinase A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In canine myocardium, the β-subunit of the L-type Ca2+ channel is phosphorylated by cAMP dependent protein kinase in vitro as well as in vivo (Haase et al. FEBS Lett 335: 217–222, 1993). We have assessed the identity of the β-subunit as well as its in vivo phosphorylation in representative experimental groups of catecholamine-challenged canine hearts. Adrenergic stimulation by high doses of both noradrenaline and isoprenaline induced rapid (within 20 sec) and nearly complete phosphorylation of the Ca2+ channel β-subunit. Phosphorylation in vivo was about 4-fold higher as compared to untreated controls. When related to catecholamine-depleted (reserpine-treated) hearts noradrenaline and isoprenaline increased the in vivo phosphorylation of the β-subunit even 8-fold. This phosphorylation correlated positively with tissue levels of cAMP, endogenous particulated cAMP-dependent protein kinase (PKA) and the rate of contractile force development dP/dtmax. The results imply the involvement of a PKA-mediated phosphorylation of the Ca2+ channel β-subunit in the adrenergic stimulation of intact canine myocardium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408645
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  • 10
    Electronic Resource
    Electronic Resource
    β2-Adrenoceptor activation by zinterol causes protein phosphorylation, contractile effects and relaxant effects through a cAMP pathway in human atrium (1996)
    Springer
    Molecular and cellular biochemistry 163-164 (1996), S. 113-123 
    Details
    ISSN: 1573-4919
    Keywords: human atrium ; β2-adrenoceptors ; receptor binding ; zinterol ; adenylyl cyclase stimulation ; atrial relaxation and contraction ; protein phosphorylation ; troponin I ; C-protein ; phospholamban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Evidence from ventricular preparations of cat, sheep, rat and dog suggests that both β1-adrenoceptors (β1AR) and β2-adrenoceptors (β2AR) mediate positive inotropic effects but that only β1AR do it through activation of a cAMP pathway. On the other hand, our evidence has shown that both β1 AR and β2 AR hasten relaxation of isolated human myocardium consistent with a common cAMP pathway. We have now investigated in the isolated human right atrial appendage, a tissue whose β-AR comprise around 2/3 of β1AR and 1/3 of β2AR, whether or not β2AR-mediated effects occur via activation of a cAMP pathway. We carried out experiments on atria obtained from patients without advanced heart failure undergoing open heart surgery. To activate β2AR, we used the β2AR-selective ligand zinterol. Experiments were carried out on paced atrial strips (1 Hz) and tissue homogenates and membrane particles. Zinterol caused positive inotropic and lusitropic (i.e. reduction of t1:2 of relaxation) effects with EC50 values of 3 and 2 nM, respectively. The zinterol-evoked effects were unaffected by the β AR-selective antagonist CGP 20712A (300 nM) but blocked surmountably by the β2AR-selective antagonist ICI 118551 (50 nM) which reduced both EC50 values to 1 μM. Zinterol stimulated adenylyl cyclase activity with an EC50 of 30 nM and intrinsic activity of 0.75 with respect to (−)-isoprenaline (600 μM); the effects were resistant to blockade by CGP 20712A (300 nM) but antagonised surmountably by ICI 118551 (50 nM). Zinterol bound to membrane PAR labelled with (−)-[125I] cyanopindolol with higher affinity for β2AR than for β- 1 AR; the binding to β2AR but not to β- BAR was reduced by GTPyS (10 μM). In the presence of CGP 20712A (300 nM) (−)-isoprenaline (400 μM); (to activate both β1AR and β2AR maximally) and zinterol (10 μM); increased contractile force 3.4-fold and 2.5-fold respectively and reduced relaxation tut by 32% and 18% respectively. These effects of (−)-isoprenaline and zinterol were associated (5 min incubation) with phosphorylation (pmol P/mg supernatant protein) of troponin I and C-protein to values of 8.4 ± 2.0 vs 12.4 ± 2.3 and 10.1 ± 2.5 vs 8.6 ± 1.6 respectively. (−)-Isoprenaline and zinterol also caused phosphorylation of phospholamban (1.8 ± 0.3 vs 0.4 ± 0.1 pmol P/mg respectively) specifically at serine residues. We conclude that in human atrial myocardium activation of both β1AR and β2AR leads to cAMP-dependent phosphorylation of proteins involved in augmenting both contractility and relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408647
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