Time-dependent alterations of nucleic acids, intracellular proteins and electrolytes in tissues of post-mortem rats

Abstract

The study is to determine post-mortem changes in nucleic acids in brain and liver, electrolytes and protein levels in brain and kidney, and to evaluate its relation with post-mortem interval (PMI). Twenty-five male Wistar rats (122.2 ± 8.29g) were sacrificed by cervical dislocation, five rats used for immediate dissection (PMI=0); the remaining 20 rats were kept in their cages under the same environmental conditions in other to allow natural decomposition. Four more groups of five rats each were taken and dissected PMI of 15, 18, 24 and 48 hours. The intracellular levels of DNA and RNA in brain and liver were determined by UV spectrophotometry. The sodium (Na), potassium (K), calcium (Ca), phosphate (PO4 2-), and iron (Fe) concentration, were determined. Brain nucleic acids and proteins showed significant changes at p<0.05 with increasing PMI, while K showed significant changes throughout the 48 hours with very high correlation values (r = -0.9). There was decrease in kidney K, and protein while calcium levels increased significantly. The relationship for rat PMI =-109.409 x K + concentration in mg/g of kidney + 161.05) was obtained. These results suggest that brain intracellular electrolytes, nucleic acids and Kidney K, and proteins may be useful for determining PMI.