Key result
Ouabain increased oxygen consumption fourfold and elevated intracellular calcium in arrested guinea-pig hearts only when extracellular calcium was present.
Why the study?
Does extracellular Ca2+ mediate ouabain-induced potentiation of cardiac basal energy expenditure in arrested guinea-pig hearts?
Population
Arrested guinea-pig whole-hearts, quiescent ventricular trabeculae, and mathematical modelling (Oxsoft Heart)
Comparison
Perfusion with ouabain in the presence of… vs Perfusion with ouabain in the absence of…
Design
Preclinical
Authors
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Supports pump-inhibition hypothesis in diastole; hypothesis-generating from animal data and leaves clinical translation open.
Does extracellular Ca2+ mediate ouabain-induced potentiation of cardiac basal energy expenditure in arrested guinea-pig hearts?
Extracellular calcium influx is mandatory for the potentiation of cardiac basal metabolism by cardiac glycosides, supporting the pump-inhibition hypothesis even during diastole.
Cooper et al. (2003) studied this question. Ouabain vs. Absence of extracellular Ca2+ was evaluated on Rate of oxygen consumption (Vo2) and intracellular Ca2+ concentration. Ouabain increased oxygen consumption fourfold and elevated intracellular calcium in arrested guinea-pig hearts only when extracellular calcium was present.
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