The Molecular Biology Mechanism And Clinical Significance Of Ischemic Precondition (IP) Of Myocardium

Objectives Ischemic precondition(IP) can protect the myocardium from ischemic injury. The research has showed that the anti-oxidase system play a significance role on IP before. In our experiment,the model of myocardial infarction, IP, Pharmacologic precondition (PP) were used to study the serum Mn-SOD and the expression of the iNOS,ICAM-1 in the infarction myocardium, in order to clarify its roles in the IP.We also tested the protection role of PP of adenosine on ischemic and infarction myocardium, in order to provide a new method for the prevention and cure of the coronary heart disease (CHD).Methods 140 adult Wistar rats were randomly divided into sham-operated group (A),control group (B),infarct group(B), adenosine PP group (C), one cycle of IP group (D1), two cycles of IP group (D2), three cycles of IP group (D3), four cycles of IP group (D4). Triphenyl tetrazolium chloride(TTC) method was used to study the percentage of the infarction area;oxidation reduction enzyme method was used to study the Mn-SOD of serum; the immunohisto-chemistry method was used to study the expression of the ICAM-1 and iNOS in the infarction myocardium.Results (1) IP can reduce the infarction area apparently, but the protective role of the IP was not increased with the IP cycles, it reaches a peak at three cycles of IP and then decrease from four cycles.(2) The content of the Mn-SOD in the serum increased after IP compared with the control group (p<0.05). With the cycle increased the content of the Mn-SOD also were increased.The peak was three cycles and then decreased from the four cycles.(3) The expression of the ICAM-1 after IP in the myocardium decreased compared with the control group (p<0.05).With the cycles increase, the expression of the ICAM-1 decreased further, and it reached a low peak at four cycles (p<0.01).(4) The expression of the iNOS in the myocardium increased after IP compared with the control group (p<0.05). With the cycles increase, the expression of the iNOS also increased, and it reached a peak at four cycles (p<0.01).(5) The adenosine PP also can reduce the infarction area, and its function is similar with two cycles. The content of the Mn-SOD in the serum, the expression of the the iNOS also increased after adenosine PP, and the expression of ICAM-1 decreased after adenosine PP too.Conclusions (1) IP can reduce the infarction area apparently;(2)The content of the Mn-SOD in the serum increased after IP, it may play an important role in IP;(3)The expression of the ICAM-1 after IP in the myocardium decreased, it may association with the pretection role of IP;(4)The expression of the iNOS in the myocardium increased after IP, it may action during IP.(5)The adenosine PP has pretection role for the ischemic myocardium.Key Word Ischemic precondition Pharmacologic precondition Mn-SOD iNOS ICAM-1 4...