D-lactate metabolism in starved Octopus ocellatus.

The concentrations of D- and L-lactate, methylglyoxal and pyruvate were measured in tissues of normal and starved Octopus ocellatus. D-Lactate was always more abundant than L-lactate in the tissues. D-Lactate, pyruvate and methylglyoxal were present in 320, 94 and 43 times higher concentrations in tentacle of O. ocellatus of control group than those in normal rat skeletal muscle. The D-lactate concentration in the tentacle of O. ocellatus was 17-fold higher than that in Octopus vulgars. The activities of enzymes involved with D-lactate metabolism such as pyruvate kinase, octopine dehydrogenase, glyoxalase I and II and lactate dehydrogenase were measured in those tissues. The activities of glyoxalase I and II, and D-lactate dehydrogenase were increased in mantle and tentacle of starved octopus, while the levels of D-lactate and related metabolites were lowered in these tissues. The experimental results presented in this report and up to the present indicate that D-lactate is actively used for energy production in the tentacle and mantle of the starved animals. In octopus, especially starved octopus D-lactate was actively produced from methylglyoxal, which is formed via aminoacetone from threonine and glycine.