A Study Of The Relationship Between The Postmortem Interval And The Degradation Of Cardiac Troponin I And Skeletal Troponin I In Rats

Objective:To study the degradation of cardiac troponin I (cTnI) and skeletal troponin I (sTnI) both in vivo and in vitro in rats .To explore the feasibility of evaluation of the postmortem interval (PMI) according to the degradation of cTnI and sTnI. To provide a method to estimate PMI for forensic medicine practiceput aintoeMethods:10 healthy SD rats were divided evenly into two groups randomly by two kinds of disposal: in vivo and in vitro. After all the rats died from mechanical asphyxia, the isolated cardiac muscle tissue and skeletal muscle tissue of 5 rats were put into a box which could prevent water evaporating,then the box as well as the other five rats'bodies were put into a artificial climate incubator to be preservated. The temperature and humidity inside the incubator should be kept respectively at 30℃and 40% .And the protein was extracted at 0,24,48,72,96,120h after the muscle were put out.Then Using Western Blot and image analysis techniques, the contents of cTnI and sTnI were determined semiquantitatively. The relative degradation speed was represented by the percentage of cTnI (sTnI)in 120 h after death and that in the immediate death . The data collected were analyzed by statistical analysis .And the binomial regress equations were caculated and the coefficient of correlation were gotten. The degradationds of cTnI and sTnI were analyzed and compared in vivo and in vitro.Results:1,The contents of both cTnI and sTnI in rats were gradually decreasing with the extension of the postmortem interval, and they both showed a proximate linear relationship with the postmortem interval.2,The degradation speeds of cTnI and sTnI in vivo were slower than those in vitro.3,The degradation speed of sTnI was slower than that of cTnI, whether in vivo or in vitro.Conclusion:1,cTnI and sTnI are hopefully to be used in estimating the late postmortem interval.2,The degradations of cTnI and sTnI in vivo are not exactly the same as those in vitro.3.,sTnI and cTnI are preferable for the estimation of the late postmortem interval.