Influence of pyruvate on economy of contraction in isolated rabbit myocardium.
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.


OBJECTIVE
We investigated the influence of pyruvate on contractility and oxygen consumption in isolated isometric contracting rabbit myocardium compared to beta-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 microM) produced a comparable increase in developed force from 21.4+/-8.3 to 67.3+/-15 mN/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).


CONCLUSIONS
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.
Keweloh
Boris
B
Franz-Volhard-Klinik, Universitätsklinikum Charité, Berlin, Germany.
Janssen
Paul M L
PM
Siegel
Ulf
U
Datz
Nicolin
N
Zeitz
Oliver
O
Hermann
Hans-Peter
HP
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D019289:Pyruvic Acid / Q000494:pharmacology*; D011817:Rabbits
D002316:Cardiotonic Agents; D007211:Indoles; D019289:Pyruvic Acid; D007545:Isoproterenol; C000543:cyclopiazonic acid