Effects of pyruvate on bovine heart mitochondria-mediated metmyoglobin reduction

Pyruvate can regenerate NADH through a variety of biochemical processes. However, no meat science research has determined if NADH produced via pyruvate can be used for mitochondria-mediated metmyoglobin reduction. Thus, our objectives were to assess the effects of pyruvate on mitochondria isolated from bovine cardiac muscle: oxygen consumption and metmyoglobin reduction at pH 5.6 and 7.4, 25 °C in vitro. Both mitochondria and myoglobin were isolated from fresh bovine hearts (n = 5). Mitochondria were reacted with pyruvate (50 mM), succinate (positive control; 50 mM), and antimycin A (mitochondrial inhibitor; 0.01 mM) and oxygen consumption was measured using a Clark oxygen electrode. Mitochondria (3 mg/mL) and metmyoglobin (0.15 mM) were reacted with either pyruvate, succinate, or antimycin A for 3 h. Addition of succinate and pyruvate increased oxygen consumption and metmyoglobin reduction at pH 5.6 and 7.4 (succinate > pyruvate, P < 0.05). Addition of a complex III inhibitor (antimycin A) decreased (P < 0.05) oxygen consumption as well as metmyoglobin reduction associated with pyruvate and succinate. Results from the current study suggest that pyruvate can increase the ability of mitochondria to consume oxygen and reduce metmyoglobin.