Extending the pre-rigor state of fish by enhancing mitochondrial ATP synthesis
2003
Watabe, S. (Tokyo Univ. (Japan)) | Itoi, S.
Abstract In Japan, spiked fish in a pre-rigor state have extremely high commercial value, similar to that of live fish. It has been claimed that the progress of rigor mortis is slower in carp acclimated to 10 deg C than in fish acclimated to 30 deg C during storage at either 0 deg C or 10 deg C. Wild specimens of plaice captured from cold waters in winter also show retarded rigor-mortis progress at 10 deg C compared with fish captured from warm water in other seasons. Two factors are supposed to be associated with such temperature-dependent rigor-mortis progress in fish. One is intracellular Ca2+ concentration and myofibrillar adenosine triphosphate (ATP) consumption -- enhanced by the increase of Ca2+, which is released from the sarcoplasmic reticulum (SR; the Ca2+ -storing organelle in muscle) via nervous stimuli. Ca2+ uptake by SR is very low at 0 deg C due to a low activity of Ca2+ -ATPase for the Ca2+ pump. Subsequently, fish rigor mortis is accelerated at 0 deg C due to the increase of intracellular Ca2+ concentration. The other factor is ATP synthesis in mitochondria. We have recently found that the content of mitochondrial ATP synthase (FoF1-ATPase) was higher in carp acclimated to 10 deg C than in fish acclimated to 30 deg C. Oligomycin-sensitive FoF1 -ATPase activity per mitochondrial protein weight was three times higher in carp acclimated to l0 deg C than 30 deg C. Furthermore, plaice and red seabream adapted to about 10 deg C contained larger quantities of' ATP synthase than fish acclimated to about 25 deg C, irrespective of species. These changes suggest that alterations in FoF1-ATPase, functioning at the final step of ATP production, are related to the progress of rigor mortis in fish.
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