Abstract: Objective In order to find a new parameter to estimate the postmortem interval, β-actin mRNA in lung and thoracic muscle of rats was detected at different time point postmortem. Methods Rats were killed by neck dislocation and left in a temperature controlling system at 21 ℃ for 12 days postmortem. Total RNA in lung and thoracic muscle at different time point was extracted and β-actin mRNA expression was examined by RT-PCR. Semi-quantification analysis of the image of electrophoresis was performed to confirm the changes of β-actin mRNA expression. Results β-actin mRNA in lung of rats still could be detected at 12 days postmortem, but disappeared in thoracic muscle at 8 days postmortem. Conclusion The expression of β-actin mRNA in lung and thoracic muscle could be a new parameter for estimation of PMI.

Key words: postmortem interval, RT-PCR, β-actin mRNA, rat, lung, thoracic muscle