In order to elucidate the degradation of inosinic acid (IMP) in the dark muscle of fish, the levels of adenine nucleotides and their related compounds were compared in the white and dark muscles of yellowtail Seriola quinqueradiata and in common mackerel Scomber japonicas during iced storage.The struggling of 30 minutes before death affected the degradation rate of IMP in the dark muscle of yellowtail, while it did not affect in the white muscle. During iced storage, the degradation of IMP proceeded very rapidly in the dark muscle of common mackerel.IMP was degraded optimally at pH 6 and pH 8 in muscle homogenates of common mackerel. The activity in the dark muscle homogenate at pH 6 was 5 times higher than that of the white muscle homogenate, whereas the activity at pH8 was nearly the same in both muscle homogenates. The fact that the high activity at pH 6 was present in the supernatant of the dark muscle homogenate indicated that this enzyme is easily soluble in water. In view of these findings, the fact that the pH of red meat fish such as mackerel falls quickly to around 6 after death suggests that the enzyme activity is mainly responsible for the rapid IMP degradation in the dark muscle. * •‚'m'åŠw"_Šw•
Studying how and where drugs are metabolized in the brain is challenging. In an entire organism, peripheral metabolism produces many of the same metabolites as those in the brain, and many of these metabolites can cross the blood-brain barrier from the periphery, thus making the relative contributions of hepatic and brain metabolism difficult to study in vivo. In addition, drugs and metabolites contained in ventricles and in the residual blood of capillaries in the brain may overestimate drugs' and metabolites' concentrations in the brain. In this study, we examine locusts and zebrafish using matrix assisted laser desorption ionization mass spectrometry imaging to study brain metabolism and distribution. These animal models are cost-effective and ethically sound for initial drug development studies.
Cardiac muscle mitochondrial fraction was prepared from rat heart homogenate, according to the procedure of differential centrifugation fol lowing nagarse digestion. The biochemical intactness of isolated mitochon dria was identified by determining the oxygen consumption of respiratory chain. The field emission scanning microscope examination of the isolated mitochondria indicated that mitochondria maintained their structural in tegrity throughout the isolation procedure. The mitochondrial fraction treated with nagarse in the process of pre paration was identified to be intact and useful for the study of cardiac muscle mitochondria.
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