Abstract: Objective To study the relationship between the changes of microbial ATP in rat muscle tissue and the postmortem interval(PMI). Methods Healthy SD rats were sacrificed and their muscles were sampled at different postmortem intervals. The concentration of microbial ATP was detected using bioluminescent assay and the data was statistically analyzed. Results The content of microbial ATP in rat muscle tissue increased along with PMI extension and peaked on postmortem day 7, thereafter decreased gradually, but increased slight- ly on postmortem day 10 once again. The PMI correlated best with the content of microbial ATP in rat muscle tissue within 9 days. If the PMI was the independent variable, the cubic polynomial regression equa- tion was y=0.020 x3-0.166 x2-0.666 x+13.412(r2=0.989, P<0.01). Conclusion Changes of microbial ATP content in rat muscle tissue may be used for estimation of PMI. Since this assay requires only small amount of tissue with much less influence by self-decomposition, it may broaden the time range of PMI estimation.

Key words: forensic pathology, adenosine triphosphate, luminescent measurements, postmortem interval, microbes