Evaluation of post mortem stability of porcine skeletal muscle RNA

The objective of this study was to evaluate the effect of postmortem times on the quality of porcine skeletal muscle total RNA in order to consider the possibility to use postmortem material for gene expression analysis. Samples of Musculus semimembranosus were collected at 20 min, 2 h, 6 h, 24 h and 48 h postmortem from the left legs of four commercial heavy pigs. Total RNA was analysed by agarose gel electrophoresis stained with ethidium bromide and by microfluidic capillary electrophoresis on an Agilent 2100 Bioanalyzer instrument obtaining 28S:18S rRNA peak ratios and RIN values. The average RIN values of the analysed samples were 7.45 ± 0.13, 7.43 ± 0.15, 7.45 ± 0.10, 7.33 ± 0.15 and 3.95 ± 0.58 for the same postmortem times, respectively, indicating that RNA degradation was present at 48 h postmortem. In a similar experiment, carried out by other authors on beef cattle muscle total RNA extracted at different postmortem times, RNA was stable up to 8 days after death as indicated by intact 28S and 18S rRNA bands. Thus, differences among species or other environmental factors might affect the level of RNA degradation. In the porcine postmortem samples, qualitative assessment of GAPDH transcripts by PCR amplification of different cDNA fragments indicated that postmortem stages did not affect the possibility of analysing this housekeeping gene. Thus, postmortem porcine skeletal muscle can be an useful tissue to obtain gene expression based information.