Lactate Dehydrogenase in Some Insect Muscles

Abstract

IN the metabolism of mammalian muscle lactate dehydrogenase plays a key part by catalysing, during contraction, the formation of lactate from pyruvate, the major glycolytic product. On relaxation the reverse process occurs and pyruvate is metabolized via the tricarboxylic acid cycle. While there is evidence^1–3 that glycolysis is the major source of energy for muscular contraction in some insects, it is clear that other insect muscles directly utilize fats^4–6. As lactate dehydrogenase is not a component of the enzyme systems involved in fat metabolism, it is apparent that the concentration of lactate dehydrogenase in an insect muscle offers an insight into the metabolism of the contractile process.