Regulatory properties of changes in the contents of coenzyme A, carnitine and their acyl derivatives in flight muscle metabolism of Locusta migratoria

Abstract

The concentrations of coenzyme A, carnitine and their acyl derivatives in flight muscles of the locust were determined during a two hours flight. The concentration of acetyl-CoA fell sharply immediately after the onset of flight, whereas coenzyme A level remained relatively constant. Acetylcarnitine showed a gradual increase during the first half an hour of flight after which it remained at the same level. Long chain acyl-carnitines showed a steady increase throughout the entire flight period. The carnitine level decreased gradually during the first fifteen minutes of flight and then stabilized. The plot of the acetyl-CoA to CoA and acetylcarnitine to carnitine ratios shows that carnitine acetyltransferase is not at equilibrium in the resting locust, but is close to equilibrium shortly after the initiation and during maintenance of flight. A small pool of the acetyl-CoA appeared not to be in equilibrium with acetylcarnitine. A buffer function of carnitine acetyltransferase and regulatory properties of acetyl-CoA with respect to citrate synthase and pyruvate dehydrogenase are discussed.