Time course and distribution of myocyte apoptosis induced by acute ischemia in rats

AIM:Myocyte apoptosis in rats can be induced by acute ischemia, but time course and distribution of myocyte apoptosis were unclear.METHODS:DNA agarose gel electrophoresis and TdT-mediated dUTP nick end-labling(TUNEL)assay were performed to evaluate apoptosis in mycardium exposed to 45 minutes, 2 hours, 6hours, 12 hours ischemia and sham-operated rats in vivo.RESULTS:DNA ladders were clearly visible in agarosegel of DNA from ischemic myocardium exposed to 2 hours, 6 hours and 12 hours ischemia, and DNA ladders became more apparent with increasing duration of ischemia.TUNEL positive cells with apoptotic morphologic characters were present in above ischemia time, and apoptotic index increased with increasing ischemia time.The majority of TUNEL positive cells were myocytes.Apoptotic index was higher in subendocardium than in subepicardium(P<0.101), while higher in border ischemia region than in the central ischemia area(P<0.105).CONCLUSION:A time-effect relation existed between the number of apoptosis and the time range of supposed time;Apoptotic myocytes scattered inthe ischemic myocardium, mainly localized at subendocardium and ischemic border.