Experimental Study Of Myocardial Muscles Of Early Acute Myocardial Ischemia In Forensic Pathology

Objective To study acute myocardial ischemia , 70 rats had been used to produce myocardial ischemia. Nitric oxide(NO) had been measured in plasma. Endothelin (ET)and nitric oxide synthase(NOS) had been studied with immuno-histochemical technique and an image analyzer, we wish to find sensitive methods for forensic identification of acute myocardial ischemia.Methods 70 rats had been used to establish acute myocardial ischemia model by ligition of anterior descending branch of the left coronary artery.The rats were classified into 7 groups with no purpose (Every group containslO rats) and were sacrificed 0.5,1,2,3,4 and 6 hours later. One group is control group the others is experimental groups. In the control group,the sutures were passed around the coronary artery but were not tied. The normal areas, ischemic areas and cross areas were excised from the hearts to make specimens. Specimens wereobserved with electron microscope and were stained with H-E methods. We study the expression of NOS and ET in heart with immunohistochemistry and study apoptosis of cell with the flow cytometry. Blood had been collected before operation and after operationto measure NO in plasma.Results Compared with the control group,nitric oxide decreased significantly after 0.5hour of occlusion and increased after 2 hours of occlusion and reached the apex after 3 hours of occlusion. In the following time , Nitric oxide decreased again(p<0.01). Expression of NOS and ET were observed in experimental groups. Microscope showed a characteristic change of ischemic cell damage for example:loss of glycogen .break clumping and margi-nation of nuclear chromations, mitochondria with the ap-pearnce of amorphous dense bodies . The results of the flow cytometery indicated that apoptosis began immediately and peaked at 3 hours after occlusion and the number of apoptosis cell in the experimental groups were much more than that in the control group.Conclusion (1)There were not typical histopathologychanges in myocardial muscules.(2) NOS and ET expressed apparently in the early stage of the acute myocardial ischemia.(3) The apoptosis had taken place at the beginning of the occlusion and increased according to the time. ET and NOS immunochemical staining and the analyzing the apoptosis in acute myocardial ischemia may be a sensitive method to diagnose the sudden death caused by AMI in forensic medicine.