© 2007 European Society of Cardiology
Influence of pyruvate on economy of contraction in isolated rabbit myocardium
a Franz-Volhard-Klinik, Universitätsklinikum Charité, Berlin, Germany
b Abteilung Kardiologie und Pneumologie, Universität Göttingen, Göttingen, Germany
* Corresponding author. Georg-August-Universität Göttingen, Abteilung Kardiologie und Pneumologie, Robert-Koch-Str. 40, D-37075 Göttingen, Germany. Tel.: +49 551 392920; fax: +49 551 398918. E-mail address: phermann{at}med.uni-goettingen.de
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Abstract |
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Background: Treatment of acute heart failure frequently requires positive-inotropic stimulation. However, there is still no inotropic agent available, which combines a favourable haemodynamic profile with low expenditure for energy metabolism. Pyruvate exhibits positive inotropic effects in vitro and in patients with heart failure. The effect on myocardial energy metabolism however remains unclear, but is meaningful in light of a clinical application.
Aims and methods: We investigated the influence of pyruvate on contractility and oxygen consumption in isolated isometric contracting rabbit myocardium compared to β-adrenergic stimulation with isoproterenol.
Results: Pyruvate (30 mM) increased developed force from 18.7±4.1 to 50.8±12.1 mN/mm2 (n=10, p<0.01). Force-time integral (FTI) increased by 329%, oxygen consumption assessed by diffusion-microelectrode technique increased from 2.86±0.30 mlO2/min*100 g to 6.28±1.28 mlO2/min*100 g (n=7, p<0.05). Economy of myocardial contraction calculated as the ratio of total FTI to oxygen consumption remained unchanged. In contrast, while isoproterenol (10 µM) produced a comparable increase in developed force from 21.4±8.3 to 67.3±15mN/mm2 (n=7, p<0.01), FTI increased only by 260% and MVO2 increased from 2.96±0.43 to 6.12±1.01 mlO2/min*100 g (n=7, p<0.01); thus, economy decreased by 23% (n=7, p<0.05).
Conclusion: Pyruvate does not impair economy of myocardial contraction while isoproterenol decreases economy. Regarding energy expenditure, pyruvate appears superior to isoproterenol for the purpose of positive inotropic stimulation.
Key Words: Pyruvate • Heart failure • Energetics • Inotropic therapy • Oxygen consumption
Received August 30, 2006; Revised January 31, 2007; Accepted March 8, 2007
1 Current address: Department of Physiology and Cell Biology, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210-1218, USA.
2 Current address: Universitätsklinikum Hamburg-Eppendorf, Klinik und Poliklinik für Augenheilkunde, Martinistr. 52, D-20246 Hamburg, Germany.