Increased oxygen cost of contractility in the endotoxemic porcine left ventricle

Scandinavian Cardiovascular Journal : SCJ
Ebrahim AghajaniTruls Myrmel

Abstract

Myocardial oxygen consumption (MVO) in the septic myocardium is comparatively high in relation to the sepsis-induced reduction in ventricular work. Our previous studies indicate that this energetic inefficiency is due to increased energy consumption in excitation-contraction (EC) coupling, i.e. myocardial calcium handling. To further confirm this observation, we assessed the oxygen cost of contractility in anesthetized pigs before and 2 h after induction of endotoxemia (1 microg/kg endotoxin infusion over 1 h, Escherichia coli toxin, n=6). Baroreceptor reflexes were blocked by hexamethonium. Contractility was increased by stepwise dopamine infusions at baseline and 2 h after induction of endotoxemia. Oxygen cost of contractility was assessed as the relationship between myocardial contractility (E or elastance) and non-mechanical oxygen consumption (unloaded MVO), a measure of energy consumption in EC coupling or calcium handling. Non-mechanical oxygen consumption (unloaded MVO) was higher after endotoxin infusions than at baseline (0.641 +/- 0.05 vs 0.383 +/- 0.07 J/beat/100 g, p < 0.05). The relationship between unloaded MVO and E, constructed by the dopamine response, was highly linear both at baseline and endotoxemia (r2 =0....Continue Reading

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Citations

Apr 3, 2007·American Journal of Physiology. Heart and Circulatory Physiology·D KonradA Oldner

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