Postmortem metabolism of short-finned squid muscle (Illex illecebrosus)

Postmortem biochemical changes were examined in the mantle muscle of the short-finned squid (Illex illecebrosus) in relation to the physical events associated with rigor. Unlike mammalian muscle, the major muscle phosphagen is arginine phosphate rather than creatine phosphate. Arginine phosphate levels did not change dramatically during the progress of rigor development. ATP depletion was found to be closely related to glycogen depletion as is often observed in mammalian muscle. The postmortem accumulation of octopine was related to the initial muscle glycogen content at death but a significant lag in its production was observed. The postmortem conversion of glucose to glucose-6-phosphate appeared to be the rate-limiting step in the overall conversion of glycogen to octopine. The intermediates found in the postmortem catabolism of squid muscle ATP were ADP, AMP, IMP Ino and Hx. Unlike most vertebrate fishes, AMP was found to accumulate in squid before conversion to IMP whereas accumulations of IMP and Ino were less than those normally found in vertebrate muscle.