BACKGROUND: Pyruvate has been shown to increase contractile function in isolated myocardium and to improve hemodynamics in patients with congestive heart failure. We tested the hypothesis that pyruvate potentiates the inotropic response to beta-adrenergic stimulation and to elevated extracellular calcium, since this may be of potential therapeutic value in the clinical setting of acute heart failure in order to circumvent deleterious effects on energy demand as can occur during catecholamine therapy. METHODS AND RESULTS: We investigated isometrically contracting isolated multicellular muscle preparations from terminal failing human hearts at 37 degrees C, pH 7.4, and a stimulation frequency of 1 Hz. At an extracellular calcium concentration of 1.25 mM, pyruvate (10 mM) alone increased developed force (F(dev)) from 9.0+/-2.3 to 21.1+/-4.3 mN/mm(2) (n=9, P
