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  • 1
    Electronic Resource
    Electronic Resource
    Absence of reoxygenation damage in isolated heart cells after anoxic injury (1984)
    Springer
    Pflügers Archiv 401 (1984), S. 71-76 
    Details
    ISSN: 1432-2013
    Keywords: Cardiac anoxia ; Enzyme release ; Reoxygenation damage ; Mitochondrial swelling ; Contracture development ; Cell lysis ; Adult heart cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cultured adult cardiac myocytes were exposed to anoxia under substrate-free conditions and then reoxygenated. When comparing the oxygen deficient organ to the anoxic cell culture, we see that metabolic changes in the latter system proceed in a similar, yet prolonged manner, as in arrested hearts. Release of cytosolic enzymes starts with minor energetic disturbances and proceeds closely correlated to the actual ATP level. Below 2 μmol ATP/gww, an increasing number of cells becomes irreversibly damaged, above this level, 30 min reoxygenation leads to extensive recovery of the whole preparation. The results indicate that leakage of cytosolic enzymes during the early stage of anoxia is due to a gradual protein release from the individual cells and is related to reversible membrane alterations. Reoxygenation does not induce changes considered typical of the ‘oxygen paradox’. Since mechanical cell-cell interactions are absent in this model, it is suggested that aggravation of tissue damage in heart tissue reoxygenated late is mainly caused by mechanical forces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581535
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A new method for continuous measuring of respiratory quotient in a computer-assisted working heart preparation (1983)
    Springer
    Basic research in cardiology 78 (1983), S. 1-7 
    Details
    ISSN: 1435-1803
    Keywords: respiratory quotient ; working rat heart ; substrate utilization ; oxygen demand ; oxygen consumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurde eine Methode entwickelt, um an einem isolierten, arbeitenden Rattenherzen kontinuierlich den RQ sowie das Verhältnis aus O2-Verbrauch und O2-Bedarf (EQ) zu registrieren. Aus dem aktuellen RQ können Aussagen über die aktuell oxidierten Substrate gemacht werden; der EQ ist im Steady-state ein Maß für den ATP/O-Quotienten der oxidierten Substrate, außerdem kann damit eine vorübergehende O2-Schuld erfaßt werden. Für die RQ-Messung wird die O2-AVD und die CO2-Freisetzung gemessen. Da bei Verwendung eines bikarbonathaltigen Perfusionsmediums die CO2-AVD nur sehr gering gegenüber der arteriellen CO2-und Bikarbonatkonzentration ist, wird ein bikarbonatfreies Perfusat verwendet. Im Koronareffluat wird nach Absenken des pH-Wertes auf ca. 4, um das CO2/HCO 3 t- -Gleichgewicht auf die Seite des gelösten CO2 zu verlagern, der CO2-Partialdruck gemessen. Weiterhin wird fortlaufend der Ventrikeldruck, das HZV sowie der Koronarfluß registriert. Alle Meßdaten werden über einen AD-Converter in einen LSI11-Computer eingelesen. Daraus werden Herzfrequenz, max. Ventrikeldruck, dP/dtmax, O2-Verbrauch, O2-Bedarf nach Bretschneider, der RQ und der EQ errechnet. An zwei Beispielen wird dargestellt, daß dieses Modell für physiologische, metabolische und pharmakologische Untersuchungen gut geeignet ist.
    Notes: Summary A method was developed for continuous monitoring of the respiratory quotient (RQ) and the ratio of O2-consumption to O2-demand (EQ) in an isolated working rat heart preparation. The RQ allows to get informations about substrates actually oxidized in the myocardium. The EQ is a parameter which behaves reciprocally to the ATP/O of the oxidized substrates during steady state and additionally it allows monitoring of a transitory oxygen debt. For registration of RQ the arterio-venous O2-difference and the CO2-release are measured. As the CO2-production is very small compared with arterial CO2- and HCO 3 − -concentrations when using a bicarbonate buffer for perfusion, a bicarbonate-free perfusion-fluid is used. In a portion of coronary effluent the pH is lowered to shift the CO2/HCO 3 − -equilibrium to the side of dissolved CO2. Then the pCO2 is measured with a CO2-Nelectrode. Additionally, ventricular pressure, cardiac input and coronary flow are continuously registrated. All data are fed via an AD-converter into an LSI 11-computer. Heart rate, maximum ventricular pressure, dP/dtmax, oxygen demand after Bretschneider's formula, RQ and EQ are calculated. The advantages of the system described are demonstrated with two examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923188
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  • 3
    Electronic Resource
    Electronic Resource
    A new method for studying the incorporation of nonesterified fatty acids into cardiac lipids by using deuterium-labelled palmitate (1988)
    Springer
    Basic research in cardiology 83 (1988), S. 87-93 
    Details
    ISSN: 1435-1803
    Keywords: nonesterifiedfatty acids ; myocardiallipids ; stable-isotope-labelledfatty acids ; cholesterol esters ; mass fragmentography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new method for measuring the incorporation of exogenous fatty acids into myocardial lipids of working rat hearts using deuterium-labelled palmitate has been developed. After perfusing isolated hearts, the fatty acid composition of triglycerides, diglyccrides, monoglycerides, cholesterol esters, and nonesterified fatty acids (NEFA) was measured by a mass fragmentographic method. Hearts perfused only with 5 mM glucose and 1 mM lactate perfusion as basic substrates showed a significant decrease of triglyceride content, while the other lipids were not found to be significantly reduced. The fatty acid composition of all lipids were not affccted. An addition of D31-palmitate complexed to albumin at a molar ratio of 5∶1, caused a dose-dependent incorporation into triglycerides and diglycerides which suggested saturation kinetics. The tissue content of nonesterified D31-palmitate was found to be linearly related to its concentration in the perfusate. It may be of note that the concentration of the other NEFA was significantly affected neither by a fatty-acid-free perfusion nor by a perfusion with D31-palmitate. A significant incorporation of the supplied fatty acid into cholesterol esters and monoglycerides could not be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01907108
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  • 4
    Electronic Resource
    Electronic Resource
    Acyl-carnitine effects on isolated cardiac mitochondria and erythrocytes (1984)
    Springer
    Basic research in cardiology 79 (1984), S. 186-198 
    Details
    ISSN: 1435-1803
    Keywords: acyl-carnitines ; mitochondrial damage ; erythrocyte stabilization ; erythrolysis ; detergent effect ; lipid-membrane interactions ; myocardial damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of various long-chain acyl-carnitines (AC) on mitochondrial functions and red cell membrane stability were studied. Lower concentrations slightly stimulate respiration-dependent functions such as phosphorylation rate and Ca++ uptake velocity, whereas higher concentrations inhibit these functions with concomitant depression of the ATP/O ratio. The order of effectiveness among the AC is very similar for different mitochondrial function. The differences among AC in their actions on red cell stability in hypotonic media and their differences in influence on mitochondiral functions exhibit less resemblance. The relative order of erythrolytic concentrations of AC follows the order of their critical micellar concentration. Model calculations indicate that the concentrations of AC found in ischemic hearts are below those which exhibit inhibitory effects in vitro. Ultrastructural changes in mitochondria incubated with AC are different from those found in ischemic tissue. From this, it seems questionable whether the elevated AC levels in ischemic hearts are indeed as importan for the development of membrane damage as is often supposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01908305
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  • 5
    Electronic Resource
    Electronic Resource
    Myocardial fatty acid oxidation: Evidence for an albumin-receptor-mediated membrane transfer of fatty acids (1984)
    Springer
    Basic research in cardiology 79 (1984), S. 274-282 
    Details
    ISSN: 1435-1803
    Keywords: myocardial fatty acid oxidation ; oxygen consumption ; respiratory quotient ; myocardial fatty acid uptake ; dichloroacetate ; acetate ; albumin receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using a computer-assisted working rat heart preparation, which allows continuous registration of the respiratory quotient, it was tested which parameters determine fatty acid oxidation in the myocardium. Supplying albumin and palmitate in different concentrations the rate of fatty acid oxidation was measured. The UFA concentrations were calculated using stepwise equilibrium constants. When keeping constant the NEFA/albumin ratio and raising total NEFA concentration, an increase in fatty acid oxidation was found showing a saturation curve. Increasing NEFA at constant albumin concentration, however, results in a linear increase in fatty acid oxidation. Keeping constant the total NEFA concentration elevation of albumin shows an inhibitory effect. These results suggest the existence of a receptor for albumin on heart cell surface, which mediates uptake of albumin-bound NEFA. An additional supply of glucose and lactate does not show any effect on these relations. Acetate and dichloroacetate, an activator of the pyruvate dehydrogenase, are found to be competitive inhibitors of fatty acid oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01908027
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