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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 210 (1966), S. 823-824 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] AFTER pretreatmerit with reserpine, an organ usually loses its responsiveness to tyramine or other substances which act through the release of catecholamine from the postganglionic sympathetic nerve endings1. However, when such an organ is exposed to, or perfused with, norepinephrine, its ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 25 (1969), S. 763-764 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Herzen gesunder, erwachsener Ratten wurden mit Krebs-Henseleit-Bikarbonatlösung durchströmt (95% O2∶5% CO2). Bei künstlich herbeigeführter Hypoxie (95% N2∶5% CO2) erschienen die Herzmitochondrien innerhalb von 7 min bedeutend vergrössert und zu 25% miteinander verschmolzen.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Prostaglandins (PGs) E2, F2α, and I2 were examined for their effects on the electrical and mechanical activities of isolated rat, rabbit and guinea-pig hearts. All PGs produced dysrhythmias in rat hearts at low concentrations only, while higher concentrations were antiarrhythmic. Guinea-pig hearts were less responsive while rabbit hearts were completely resistant.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 77 (1982), S. 117-139 
    ISSN: 1435-1803
    Keywords: calcium movement ; cardiac physiology ; cardiac pathophysiology ; calcium regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es ist allgemein anerkannt, daß Calcium von besonderer Bedeutung für die Funktion der Myokardzelle ist. Trotzdem ist über die genaue Natur der Calcium-Wirkung sowie auch über die mögliche Bedeutung von Calcium für das Absterben einer Myokardzelle wenig bekannt. Fortschritte in der Erforschung der Calcium-Bewegungen im Herzen ermöglichen neue Vorstellungen über die Rolle des Calciums unter physiologischen und pathophysiologischen Bedingungen. Offensichtlich bestehen enge Beziehungen zwischen Calcium-Bewegungen und elektrophysiologischen Abläufen, kontraktiler Funktion, Membranintegrität und Energiemetabolismus. Insbesondere wurde eine neue Theorie entwickelt, die den giemetabolismus. Insbesondere wurde eine neue Theorie entwickelt, die den Inositphosphatid-Umsatz und die Aktivierung der Ca-abhängigen ATPase berücksichtigt im Hinblick auf die Mechanismen und die Kontrolle des Calcium-Eintritts in die Zelle bei Erregung. Änderungen in der Regulierung des Calcium-Stoffwechsels können die Ca-Verteilung in der Zelle beeinflussen und dadruch Herzfunktion und Stoffwechsel verändern. Die Rolle, die Calcium bei der Entwicklung pathologischer Zustände im Myokard spielt, wird im Lichte der Forschungsergebnisse bei Verwendung unterschiedlicher experimenteller Ansätze diskutiert. Es wird postuliert, daß Überladung der Zelle mit Calcium und Calcium-Mangel der Zelle zum kontraktilen Versagen des Herzens und zum Zelltod beitragen durch eine Anzahl definierter Mechanismen. Im Hinblick auf eine sachgerechte Behandlung kardialer Störungen stellt sich daher die Aufgabe, die genaue Natur der Prozesse zu klären, die mit Calcium-Überbeladung oder Calcium-Mangel einhergehen.
    Notes: Summary It is widely recognized that calcium is of singular importance in the viability of the myocardial cell, nonetheless little is known concerning the precise nature of the action of calcium in myocardium as to how it maintains the life of the cell and how it may dictate the death of the cell. However, recent advances in research involved with the study of calcium movement in the heart have been highly valuable for the formulation of new concepts with respect to the physiological and pathological aspects of calcium metabolism in the myocardium. It is becoming clear that calcium movements are closely related to cardiac electrophysiological events, contractile function, membrane integrity and energy metabolism. In particular, a novel theory involving phosphatidylinositol turnover and Ca2+-dependent ATPase activation has been advanced regarding the mechanism and control of calcium entry into the cardiac cell upon excitation. Alterations in the regulation of calcium metabolism through the interaction of a number of separate, elements may affect calcium distribution in the cell and thereby may change cardiac function and metabolism. The part calcium plays in the genesis of pathological states in the myocardium is discussed in the light of research employing various experimental protocols. Intracellular calcium overload and deficiency are postulated to contribute to cardiac contractile failure and cell death through a number of distinct mechanisms. It is now a real challenge to understand the precise nature of processes associated with the occurrence of intracellular calcium overload or intracellular calcium deficiency in order to achieve proper management of cardiac disorders.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 78 (1983), S. 451-461 
    ISSN: 1435-1803
    Keywords: isolated sarcolemma ; cell surface material ; sialic acid ; membrane sidedness ; sarcolemmal enzymes ; calcium binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two different procedures were employed for the isolation of sarcolemma from the rat heart and the membranes were studied with respect to the presence of cell surface material as well as their functional characteristics. Both hypotonic shock-LiBr treatment method (fraction HL) and sucrose density gradient method (fraction S) yielded membranes enriched 8 to 13 fold with respect to Na+−K+ ATPase and adenylate cyclase activites in comparison to heart homogenate. Cell surface material was demonstrated on the outer surface of the vesicles only in fraction HL with cationic dyes, lanthanum and ferritin, applied either to the isolated fractions or perfused in the heart through coronaries. Fraction HL also had high sialic acid content. ATP independent Ca2+ binding in fraction HL was about 6 times more than that in fraction S which had little sialic acid and showed no cell surface staining with cationic dyes. On the other hand, ATP-dependent Ca2+ binding and Ca2+-stimulated Mg2+ dependent ATPase activities in fraction S were 4 to 6 times higher than those in fraction HL. Epinephrine stimulated adenylate cyclase in fractions HL and S by 24 and 3% whereas ouabain was found to inhibit Na+−K+ ATPase in these fractions by 80 and 10% respectively. A mild treatment of the membranes with deoxycholate to eliminate the semipermeable characteristics or effects of sidedness of the vesicles resulted in an almost complete ouabain inhibition of Na+−K+ ATPase in both fractions. These data suggest that presence of cell surface material as well as membrane sidedness has an important role inin vitro expression of functional characteristics of sarcolemma. It is emphasized that sarcolemmal preparations containing cell surface material will provide information more realistic to the native conditionsin situ.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 82 (1987), S. 271-278 
    ISSN: 1435-1803
    Keywords: diabetes ; lysomal enzymes ; diabeticcardiomyopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Alterations in the cardiac tissue and serum acid hydrolase activities were studied in chronic streptozotocin-induced diabetes in rats. No changes were observed in total cardiac tissue homogenate lysosomal enzyme activities at 4 weeks of diabetes but there were significant alterations in the distribution of selected enzymes. Significant decreases in nonsedimentable β-N-acetylglucosaminidase (NAG) and β-galactosidase (Gal) activities were observed at 4 weeks of diabetes. At 8 weeks of the disease, decreased activities of NAG and Gal were observed in heart homogenates but no changes were apparent in α-mannosidase (Man) or acid phosphatase activities. Nonsedimentable activities of NAG and both sedimentable and nonsedimentable activities of Gal were decreased at 8 weeks. At 16 weeks of the diabetic condition, increased activities of NAG, Gal and acid phosphatase were observed. This increase at 16 weeks of the disease was due to an increase in sedimentable enzyme activity. At all times of diabetes, serum enzyme activities were significantly increased. Insulin treatment reversed all of the observed changes in tissue homogenates, but serum levels were not completely reversed. These results suggest that cardiac lysosomal hydrolases are probably only involved in the later stages of the diabetic cardiomyopathy when extensive ultrastructural derangements are evident. The present evidence also suggests that the heart may be a source of serum hydrolase activities.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1435-1803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei katheterisierten Kaninchen wurde Streptococcus viridans bzw. Kochsalzlösung (bei Kontrolltieren) injiziert und der Zeitverlauf der Veränderungen in der Herzaktion der myokardialen Ultrastruktur (Membransysteme, Myofibrillen) sowie dem Gehalt an Kationen, zyklischem AMP, Noradrenalin und energiereichem Phosphat verfolgt. Sowohl bei in infizierten als auch bei den nichtinfizierten Tieren ergab sich, daß die Myokardhypertrophie einer verstärkten Aktivität des sympathischen Nervensystems folgt, wie aus der Steigerung der Herzfrequenz sowie des Gehaltes an Noradrenalin- und zyklischem AMP hervorging. Der Rückgang in der Aktivität der sarkolemmalen Na+−Ka+-ATPase-Aktivität war von kontraktilem Versagen begleitet und ging einem Abfall des myokardialen K+-Gehalts und einem Anstieg des Na+-Gehalts voraus. Die Minderung der sarkolemmalen Ca2+-Bindungsaktivität könnte zu einem Rückgang der Ca2+-Aufnahme beitragen und die Minderung des myokardialen Ca2+-Gehaltes und der kontraktilen Aktivität erklären. Diese Veränderungen waren auch von einer reduzierten mikrosomalen Ca2+-Bindung und von einer verminderten mitochondrialen RCI begleitet. Eine reduzierte Aktivität der oxidativen Phosphorylierung in den Mitochondrien bewirkte einen Rückgang der Vorräte an energiereichem Phosphat. Ein Abfall der sarkolemmalen, mitochondrialen und myofibrillären ATPase-Aktivität und der sarkolemmalen Adenylatcyclase wurde in späteren Stadien der bakteriellen Endokarditis beobachtet, in denen auch ausgedehnte Zellschädigungen vorlagen. Diese Beobachtungen lassen vermuten, daß die myokardiale Hypertrophie bei bakterieller Endokarditis Folge eines erhöhten Spiegels an zyklischem AMP ist, während das nachfolgende Herzversagen und die Zellschädigung bei dieser Erkrankung auf Defekte verschiedener Membransysteme-begleitet von myokardialem Ca2+-Defizit-bezogen werden kann.
    Notes: Summary Rabbits were catheterized and injected with saline (uninfected) orStreptococcus viridans (infected) to study the time course of changes in heart function, ultrastructure, membrane systems, myofibrils, and myocardial cations, cyclic AMP, norepinephrine and high energy phosphate contents. Myocardial hypertrophy in both infected and uninfected animals was found to follow increased activity of sympathetic nervous system as indicated by increased heart rate as well as norepinephrine and cyclic AMP contents. The decrease in sarcolemmal Na+−K+ ATPase activity was associated with contractile failure and preceded the observed decrease in myocardial K+ and increase in Na+ contents. The decrease in sarcolemmal Ca2+ binding activity may contribute in decreasing calcium entry and explain decreased myocardial Ca2+ contents and contractile activity; these changes were also accompanied by decreased microsomal calcium binding as well as depressed mitochondrial RCI. Depression in mitochondrial oxidative phosphorylation activity was found to result in declining high energy phosphate stores. Decreases in sarcolemmal, mitochondrial and myofibrillar ATPase activities as well as sarcolemmal adenylate cyclase activity were observed in late stages of bacterial endocarditis, at which time extensive myocardial cell damage was also apparent. These observations suggest that myocardial hypertrophy due to bacterial endocarditis may be a consequence of elevated levels of cyclic AMP whereas subsequent heart failure and cell damage in this disease may be due to defects in different membrane systems accompanied by a myocardial calcium deficiency.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 85 (1990), S. 45-54 
    ISSN: 1435-1803
    Keywords: freeradicals ; hydrogen peroxide ; Ca2+-ATPase ; Ca2+-binding ; heart sarcolemma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of oxygen free radicals on Ca2+/Mg2+ ATPase and ATP-independent Ca2+-binding activities were examined in rat heart sarcolemma. Membranes were incubated with different oxygen radical generating media such as xanthine + xanthine oxidase, hydrogen peroxide, and hydrogen peroxide + Fe2+. In the presence of xanthine + xanthine oxidase, Ca2+ ATPase activity was stimulated and this effect was prevented by the addition of superoxide dismutase. Hydrogen peroxide also showed a significant increase in Ca2+-ATPase activity in a dose-dependent manner and this effect was blocked by catalase. On the other hand, a combination of hydrogen peroxide + Fe2+ decreased Ca2+-ATPase activity; this depression was prevented by the addition of D-mannitol. The observed change in Ca2+-ATPase activity due to oxygen free radicals was associated with changes in Vmax, whereas Ka remained unaffected. Both xanthine + xanthine oxidase and hydrogen peroxide increased whereas, hydrogen peroxide + Fe2+ inhibited the ATP-independent Ca2+-binding activities. It is suggested that oxygen free radicals may influence Ca2+ movements in the cell by altering the Ca2+/Mg2+ ATPase and Ca2+-binding activities of the membrane and these effects may be oxygen-radical species specific.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 79 (1984), S. 620-626 
    ISSN: 1435-1803
    Keywords: heart sarcolemma ; Ca2+-stimulated ATPase ; ATP-dependent Ca2+ binding ; β-adrenergic antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of some β-adrenergic antagonists such as acebutolol, propranolol, pindolol and oxprenolol (1–1000 μM) were studied on the rat heart sarcolemmal Ca2+ transport activities. Pindolol enhanced sarcolemmal ATP-dependent Ca2+ binding and Ca2+-stimulated ATPase whereas acebutolol had no effect. Both propranolol and oxprenolol had biphasic actions on the sarcolemmal Ca2+ pump activities; the lower concentrations (1 and 10 μM) were stimulatory, but the higher concentrations (100 and 1000 μM) were inhibitory. None of the drugs used in this study had any effect on Mg2+ ATPase and non-specific Ca2+ binding activities of heart sarcolemma except that 1000 μM propranolol decreased Mg2+ ATPase activity significantly. Mitochondrial and microsomal ATP-dependent Ca2+ binding activities were unaffected by these drugs (1–1000 μM), except that 1000 μM propranolol was inhibitory. These results suggest differences among various β-adrenergic blocking drugs with respect to their actions on sarcolemmal Ca2+ pump in the myocardium.
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  • 10
    ISSN: 1435-1803
    Keywords: cardiac hypertrophy ; myosin ATPase ; actin-activated myosin ATPase ; myofibrillar ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A non-failing hypertrophy of the left ventricle was produced in the pig heart by supravalvular banding of aorta for 4, 8 and 12 weeks and the myosin and myofibrillar adenosine triphosphatase activities were measured. A significant increase in myosin Ca2+-ATPase activity was seen at 4 weeks of hypertrophy, but at 8 and 12 weeks this activity was significantly decreased compared to sham control. Similar changes were also seen in actin-activated myosin ATPase activities at 4, 8 and 12 weeks of hypertrophy. There were no changes in the K+- and NH4 +-EDTA-stimulated ATPase activities of myosin. Basal ATPase activities of myofibrils were decreased at 4 and 8 weeks of hypertrophy and there was no change in this activity at 12 weeks of hypertrophy. Ca2+ stimulated ATPase activity of myofibrils was significantly increased at 4 weeks, normal at 8 weeks and significantly reduced at 12 weeks of hypertrophy. The changes in ATPase activities were not due to any alterations of proteins by high concentrations of salts during the purification of myosin. The non-hypertrophied right ventricle from the banded animals did not show any change in the basal or Ca2+ stimulated myofibrillar ATPase activities. It is suggested that hypertrophy of the myocardium is accompanied by specific changes in the enzyme activities of the contractile proteins and the biphasic responses may correlate with the functional state of the myocardium subjected to a chronic increase in pressure.
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