name for a number of enzymes, including: l-lactate dehydrogenase (cytochrome), d-lactate dehydrogenase (cytochrome), l-lactate dehydrogenase, and d-lactate dehydrogenase. The first two enzymes transfer hydrogen to ferricytochrome c or to cytochrome b2, the last two transfer it to NAD+, in catalyzing the oxidation of lactate to pyruvate; the isozyme distribution of heart and muscle lactate dehydrogenase is of significant use in cases of myocardial infarction; a deficiency of a subunit will result in myoglobinuria after intense exercise. SYN: lactic acid dehydrogenase.