Key result
Valinomycin at 0.05 micrograms/ml reduced heart rate by 50% and max dP/dt by 90% in isolated perfused rat hearts, alongside decreased myocardial energy charge and increased lactate.
Why the study?
Does valinomycin alter function and metabolism in isolated perfused rat hearts?
Does valinomycin alter function and metabolism in isolated perfused rat hearts?
Valinomycin profoundly depresses cardiac function and alters myocardial energy metabolism in isolated rat hearts, characterized by reduced energy charge and increased glycolysis.
Valinomycin impairs isolated rat heart performance; leaves open translational relevance to intact animals or clinical settings.
Valinomycin, a K(+)-specific ionophore, influenced function and metabolism of isolated perfused rat hearts in a dose-dependent fashion. At a concentration of 0.05 micrograms ml-1 in perfusion fluid a 50% reduction of heart rate (HR) and a 90% reduction in max dP/dt were observed. These effects were paralleled by a substantial decrease of myocardial energy charge from about 0.80 to 0.20. A 2.5 fold increase in tissue lactate concentration indicated an increased rate of glycolytic activity. Low ATP combined with high ADP and AMP levels as found in these valinomycin-treated hearts is known to promote phosphofructokinase activity and may explain the elevated lactate levels. A significant increase in the concentrations of adenosine, IMP and inosine was observed as well.
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Martinussen et al. (1993) studied isolated perfused rat heart. Valinomycin was evaluated on heart rate (HR) and max dP/dt. Valinomycin at 0.05 micrograms/ml reduced heart rate by 50% and max dP/dt by 90% in isolated perfused rat hearts, alongside decreased myocardial energy charge and increased lactate.
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