title: Effects of lactate on beef heart mitochondrial oxygen consumption and muscle darkening.
abstract: The mechanism of lactate-induced beef color darkening is unclear. Our objective was to evaluate the ability of mitochondria isolated from bovine cardiac muscle to utilize lactate as a fuel for respiration. Addition of lactate (4, 8, and 16 mM) to isolated bovine cardiac mitochondria resulted in state IV oxygen consumption at pH 7.2 and 25 degrees C measured using a Clark oxygen electrode. Combining mitochondria with lactate, LDH, and NAD increased state IV oxygen consumption compared with that of lactate alone (p < 0.05). Moreover, oxygen consumption resulting from the addition of lactate-LDH-NAD (0.2 mM each) was comparable to oxygen consumption resulting from the direct addition of NADH (0.2 mM) to mitochondria at pH 7.2. Rotenone reduced (p < 0.05) lactate-mediated darkening in bovine cardiac muscle homogenates. Lactate-induced beef color darkening may be due to increased oxygen consumption by mitochondria, which out-competes myoglobin for oxygen and results in dark colored muscle.
authors.affiliation: Department of Animal Science, University of Connecticut, Storrs, Connecticut 06269-4040, USA.
authors.forename: Ranjith
authors.initials: R
authors.lastname: Ramanathan
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mancini
authors.forename: Muralikrishna Reddy
authors.initials: MR
authors.lastname: Konda
mesh_terms: D000818:Animals; D002417:Cattle; D003116:Color; D019344:Lactic Acid / Q000494:pharmacology*; D008460:Meat; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism*; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D012402:Rotenone / Q000494:pharmacology*
chemical_list: D009211:Myoglobin; D012402:Rotenone; D019344:Lactic Acid