| In recent years, extensive application of thrombolytic therapy after myocardial infarction, coronary artery bypass surgery and percutaneous coronary angioplasty brings favorable effects on saving ischemic myocardium,reducing the myocardial infarction area and improving the clinical symptoms. However, these therapies could lead to myocardial ischemia reperfusion injury (MIRI),which becomes the key factor that influences surgical effect and patient outcomes. Thus,finding a way to reduce the ischemia reperfusion injury (IRI) is of great importance.Prostaglandin E1(PGE1) can inhibit platelet aggregation, thromboxane A2 generation, the formation of atherosclerosis lipid plaque and immune complex. In addition, PGE1 is able to dilate peripheral and coronary vessels. Many studies of tutors'group had been done on protecting myocardium of PGE1, which had confirmed that PGE1 can improve hemodynamic changes of myocardial ischemia-reperfusion;effectively reduce the leakage of CPK and LDH, lighten the damage of myocardial ultrastructure; enhance the activity of SOD, reduce the generation of MDA and relieve the MIRI by anti-myocardial lipid peroxidation; increase the expression of bcl-2, inhibit the expression of bax and restrain obviously the apoptosis of myocardial hypoxia/reoxygenation; improve the level of myocardial Gαq/11, promote the open of KATP channels, reduce calcium overload;promote the expression of HSP and PKC,raise the ability of myocardial stress, protect the I/R myocardium. However, NF-KB-mediated inflammatory damage of PGE1 preconditioning in isolated rat and the expression of ICAM-1 and the link between NF-ΚB and ICAM-1 have not been reported yet. In this study, we had investigated the expression of NF-ΚB and ICAM-1 using Western blot and immunohistochemical method to explore their roles on PGE1 preconditioning myocardium of isolated rat with IRI, which may provide theory basis for a wide application of PGE1 as an effective pharmacological preconditioning drug on preventing cardiovascular disease.Objective:The model of myocardial ischemia reperfusion injury was established in isolated rat heart perfused with Langendorff technique to investigate the effects of NF-ΚB and ICAM-1 expression in preconditioning myocardium with ischemia reperfusion injury and reveal the possible mechanism of PGE1 protective effect from inflammatory signaling pathways.Methods:Adult and healthy SD rats were applied in this study and divided into five groups at random:normal control group, ischemia/reperfusion group and the low,middle,high doses of PGE1 preconditioning groups (14μg/L,42μg/L,126μg/L), each group had eight rats.The hearts of rats were perfused with normal desktop-liquid for 15 min to equilibrium firstly, then perfused with normal desktop-liquid for 3 hours in the normal control group; in the ischemia/reperfusion group, perfused with the normal desktop-liquid for 30 min followed by global ischemia for 30 min, and then reperfused with the normal desktop-liquid for 2 hours; in the different doses of PGE1 preconditioning group, perfused with the normal desktop-liquid containing different doses of PGE1 for 30 min followed by global ischemia for 30 min,and then reperfused with the normal desktop-liquid for 2 hours. After perfusion take out the left ventricular antetheca quickly and divide it into two parts:one part was fixed to make the pathological slices for HE staining to observe the pathomorphological changes of the rat myocardial fibers and for immunohistochemical method to measure the changes of NF-κB and ICAM-1 expression; the other part was freezed in liquid nitrogen for Western blot to detect semiquantitatively the change of NF-κB expression in myocardium. The data were applied to the single-factor analysis of variance by SPSS 17.0 and demonstrated with mean±tandard deviation(x±s), the comparison between groups were analyzed with LSD method, a=0.05 was considered as the significant level.Results:1The morphological changes of cardiac muscle tissueObserved under light microscope, there was not unusual changes in normal control group. Cardiac muscle fibres were integrated and showed uniform staining.The cardiac myocytes were closely-arranged,whose striations were legible. It had not seen dilated vessels and inflammatory cells infiltrating in the interstitial.In I/R group,a wide range of cardiac muscle fibres were fractured, swollen and necrotic. The staining was uneven. The myocytes were arranged irregularly, whose striations were disappeared.The vessels could be seen significantly expansive and there were a number of inflammatory cells infiltrating in the interstitial.In low doses (14μg/L) of PGE1 preconditioning group,larger range of cardiac muscle fibres were fractured and swollen.The myocytes were arranged disorderly and part of striations were disappeared. There were vessels expanding and inflammatory cells infiltrating in interstitial, which were inferior to the ischemia/reperfusion group.In middle doses (42μg/L) of PGE1 preconditioning group,the myocardial fibres were still swollen but seldom fractured,the vessels were not significantly expansive and a little of inflammatory cells infiltrated in the interstitial.In high doses (126μg/L) of PGE1 preconditioning group, the myocardial fibres were seldom swollen and not fractured. In the interstitial vessels were not seen expansive and inflammatory cells could be seen accidently.The morphology was similar to the normal control group.2 The changes of NF-κB and ICAM-1 expression observed from immunohistochemistry(1)Compared with normal control group (19.99±4.59), the expression level of NF-κB in I/R group (47.36±3.27) increased significantly (P<0.05). Compared with I/R group, the expression level of NF-κB decreased significantly in the different doses of PGE1 preconditioning groups (14μg/L,42μg/L,126μg/L)(P<0.05), 39.29±2.63,30.49±3.24,24.41±4.00 respectively. There were statistical differences among different doses of PGE1 preconditioning groups (P<0.05).(2)Compared with normal control group (22.98±5.28), the expression level of ICAM-1 in I/R group (50.26±7.04) increased significantly (P<0.05). Compared with I/R group, the expression level of ICAM-1 decreased significantly in the different doses of PGE1 preconditioning groups (14μg/L,42μg/L,126μg/L)(P<0.05), 42.28±4.69,34.96±4.01,29.51±4.82 respectively. There were statistical differences among different doses of PGE1 preconditioning groups (P<0.05).3 The change of NF-κB expression observed from Western blotCompared with normal control group (0.278±0.015), the expression level of NF-κB in ischemia/reperfusion group (0.842±0.016) increased significantly (P< 0.05). Compared with I/R group, the expression level of NF-κB decreased significantly in the different doses of PGE1 preconditioning groups (14μg/L,42μg/L,126μg/L)(P<0.05),0.682±0.023,0.527±0.019,0.390±0.015 respectively. There were statistical differences among different doses of PGE1 preconditioning groups (P <0.05).Conclusion:1 PGE1 preconditioning could improve the morphological changes of ischemia/reperfusion myocardial fibre, and effectively reduce ischemia reperfusion injury of isolated heart.2 PGE1 may inhibit the expression of NF-κB and ICAM-1 in order to reduce the myocardial inflammation mediated PMN. It is one of the possible mechanisms of PGE1 anti- myocardial ischemia reperfusion injury.3 NF-κB plays a role in the myocardial ischemis reperfusion injury through regulating the expression of ICAM-1. |
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