Bernd Siegmund

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In tissue, mechanical cell-to-cell interactions may contribute to cardiomyocyte injury in anoxia-reoxygenation. In the present study, the disturbance of energy metabolism and cell injury were investigated in isolated cardiomyocytes, free of external mechanical constraints. Cardiomyocytes from adult rat, attached to culture dishes, were exposed to 120 min of(More)
Reoxygenation after 120-min substrate-free anoxia causes sudden hypercontracture in isolated rat cardiomyocytes. Reoxygenated-hypercontracted cardiomyocytes maintain their sarcolemmal integrity as indicated by the absence of enzyme release and reestablish a nearly normal free energy change of ATP hydrolysis within 15 min [Siegmund, B., A. Koop, T. Klietz,(More)
Effects of Na+/H+ exchange inhibition and cytosolic acidosis on reoxygenated adult rat ventricular cardiomyocytes were investigated. Cells were incubated in anoxic media at pH 6.4 until pCa of < or = 5, intracellular pH (pHi) of 6.5, and cytosolic [Na+] of 50 mM were reached. On reoxygenation, medium pH was changed to 7.4 to activate Na+/H+ exchange. In one(More)
BACKGROUND Resupply of oxygen to the myocardium after extended periods of ischemia or hypoxia can rapidly aggravate the already existing injury by provoking hypercontracture of cardiomyocytes (acute reperfusion injury). Previous studies indicated that halothane can protect ischemic-reperfused myocardium. The aim of the present study was to analyze on the(More)
The ability of coronary endothelial cells in 14 day confluent cultures to metabolize glucose, palmitate, lactate and various amino acids was investigated. Under aerobic conditions, 99% of glucose, (5 mM) was degraded to lactate and only 0.04% was oxidized in the Krebs cycle. One percent of the glucose catabolized was directed into the hexose monophosphate(More)
When myocardial cells are reoxygenated after a prolonged period of energy depletion, they rapidly hypercontract. In tissue, hypercontracture induced by reoxygenation is accompanied by cytolysis ("oxygen paradox"). Recent studies have indicated that severe cytosolic Ca2+ overload and reactivation of energy production represent the causal key factors for the(More)
When oxygen-deprived cardiomyocytes become energy depleted, they accumulate Na+ and Ca2+ in the cytosol. Influx of Ca2+ via the Na+/Ca2+ exchange mechanism seems to contribute to the development of Ca2+ overload, but Ca2+ overload may eventually also occur when this route is blocked. Hypoxic-reoxygenated cardiomyocytes in a state of severe overload of Na+(More)
The ability of hypoxic-reoxygenated cardiomyocytes to recover from severe cytosolic Ca2+ overload was investigated using the fluorescent Ca2+ indicator fura-2 in ventricular cardiomyocytes from adult rats. When the fura-2 ratio (340/380 nm) reached saturation in hypoxic cardiomyocytes, indicating severe Ca2+ overload, they were reoxygenated. The cell then(More)
In medium 199 plus 20% fetal calf serum adult rat cardiomyocytes establish a long-term culture (25 days). During the first 10 days they change their gross morphology from the typical elongated in vivo shape (day 1), to a smooth spherical intermediate form (days 2 to 5), to a spread cell type beating spontaneously (days 10 to 15). During the first 10 days in(More)
The role of Na+ in the recovery from severe anoxic Ca2+ overload was investigated in isolated quiescent ventricular cardiomyocytes from adult rat. Changes of cytosolic Ca2+ and Na+ concentrations were followed by the fura 2 and Na(+)-binding benzofuran isophthalate techniques, respectively. When the fura 2 ratio (340/380 nm) reached saturation in anoxic(More)