New contributions to the relationship between sequential changes of ATP-related metabolites and post-mortem interval in rats

In recent years, it has become a new research direction to post-mortem interval (PMI) estimation from the changes in metabolite content generated during the process of cadaver corruption, and lead to more and more attention has been paid to the biochemical changes of muscles after death. The ATP degradation process has long been accepted as a precise manner to estimate freshness of meat products in food science. ATP-related metabolites may also serve as an indicator for PMI estimation of corpses. The purpose of this study was to test this possibility. Firstly, this study optimized the detection method of ATP-related metabolites in skeletal muscles of rat. Moreover, in animal experiment, ATP-related metabolites (ATP, ADP, AMP, IMP, Ino, Hx) in lower hind limb skeletal muscles of sixty rats were measured by RP-HPLC at different PMI for 168 h at 20 °C ± 1 °C, the change of freshness indicators (K value, K₁ value, K₀ value, H value, P value, G value, IMP ratio) were carefully analyzed, and investigate the relationship between them and PMI. The overall results showed that IMP, AMP, Hx, Total metabolites, K value, K₁ value, K₀ value, H value, P value, G value, and IMP ratio in skeletal muscles changed significantly with PMI (R² = 0.864-0.971, all P < 0.01) while ATP, ADP, Ino, IMP precursors and IMP degradants had minor changes during the same period (R² = 0.171-0.706). Specifically, significant linear positive correlations between H value of skeletal muscles and PMI were found, and the coefficients of their regression functions were R² = 0.971. The correlation between AMP and PMI was slightly lower (R² = 0.864), but the scope of PMI estimation was the widest (168 h). It can be concluded that the determination of ATP-related metabolites in skeletal muscle may be a potential tool in the PMI estimation. However, more researches on its influencing factors are needed to facilitate its final use in practice.