Abstract: To investigate law of FOS protein induced by myocardial ischemia reperfusion (MI/R) in acute period, amodel in 20 anaethetized SD rats was established. Ratswith normal and ischemia were used as control groups.Specimens were studied immunohistochemically with c fos antibody. Afer ischemia 20 minutes, followed by 30minutes reperfusion, the area of MI/R showed nuclei ofmyocytes positive staining in cryosection slides. In C2group, the area showed nuclei of myocytes (37. 76%±9. 66% ) positive staining weakly. In C3 group, nuclei ofcardiac myocytes(40. 34% ± 3. 32% ) was significantlypositive. In C4 group it began to attenuate(35. 36% ±4. 81% ). The myocardium in normal and ischemic control groups showed negative staining. No changes wereseen with HE staining. Our data indicated that immunohistochernical method may reveal acute MI/R injury ofischemia 20 min and reperfusion 30 min with anti - FOSprotein staining and there is problely a peak between 60 -120min after reperfusion. It is possible that the method beused to diagnose sudden cardiac death in forensicmedicine.

Key words: Myocardial acute ischemia reperfusion, immunohistochemical study, FOS protein